Tension-adjustable paper feeding mechanism for flexo printing machine

Abstract

The invention provides a tension-adjustable paper feeding mechanism for a flexo printing machine, and relates to the technical field of printing machines, the tension-adjustable paper feeding mechanism comprises a shaft body and a moving part, the moving part comprises an air bag and key bars, the air bag can expand or contract, the key bars are slidably connected with the shaft body and are arranged at equal intervals in the circumferential direction of the shaft body, and when the air bag expands, the key bars are pushed to extend out relative to the shaft body; as the sliding direction of the key bar is perpendicular to the axial direction of the shaft body and forms the included angle with the radial direction of the shaft body, the key bar applies extrusion force to the air bag along the sliding direction, so that the air bag rotates by a certain angle along the circumferential direction of the shaft body, the contact position of the air bag and the key bar is switched in the circumferential direction, and the air bag is uniformly pressed; the problems of local stress concentration and non-uniform thickness of the air bag are relieved, the compression strength of the air bag is ensured, the risk of breakage of the air bag is reduced, meanwhile, fatigue aging of materials is relieved, and the service life of the air bag is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of printing machines, in particular to a paper feeding mechanism with adjustable tension for a flexographic printing machine. BACKGROUND

[0002] A printing machine is a key device for realizing the copying of characters and images. A flexographic printing machine gradually replaces mechanical shaft intaglio printing equipment in the soft packaging field and becomes a mainstream technology route due to its simple structure, strong environmental protection, and fast printing speed. The core structure of the flexographic printing machine includes a paper feeding and unwinding mechanism, a printing mechanism, a drying mechanism, and a rewinding and material collecting mechanism. The paper feeding and unwinding mechanism is responsible for the stable conveying and tension initial control of the roll material. The material tension is adjusted through a guide roller group, a floating roller, and a traction device. An air inflation shaft (gas inflation shaft) is a core transmission and clamping component, which is mainly used for automatic clamping, tension control, and efficient roll changing of the roll material (such as paper and plastic film). The air inflation shaft is internally provided with an elastic air cavity. After compressed air is filled, the air cavity expands to drive the surface key to pop out and lock the inner core of the roll material. After the air is exhausted, the key is retracted to realize quick roll unloading, solve the problems of manual fixing and complicated roll changing of the traditional mechanical shaft, and improve the operation efficiency. In the flexographic printing machine, the air inflation shaft is widely used in the unwinding and rewinding stations. Through linkage with a tension brake and a servo motor, the uniform control of the release speed of the roll material is realized, and the overprint deviation during high-speed printing is reduced.

[0003] The air bag of the existing air inflation shaft is prone to plastic deformation (indentation) in the contact area with the key bottom under long-term repeated inflation and deflation cycles, which causes local stress concentration and uneven thickness of the air bag, reduces the pressure resistance of the air bag, increases the risk of air bag rupture, and accelerates the material fatigue aging, thereby shortening the service life of the air bag.

[0004] The information disclosed in the background section of the present application is only intended to deepen the understanding of the general background of the present application and should not be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art. SUMMARY

[0005] Therefore, it is necessary to provide a paper feeding mechanism with adjustable tension for a flexographic printing machine in view of the problems of the existing air inflation shaft.

[0006] The above-mentioned purpose is achieved by the following technical solutions: A paper feeding mechanism of a tension-adjustable flexographic printing machine comprises a shaft body for supporting a roll, a shaft cavity is formed in the shaft body, a gas pipe coaxial with the shaft body is arranged in the shaft cavity, a moving part is arranged on the gas pipe, the moving part comprises a gas bag and a key strip, the gas bag is annular and rotationally connected with the gas pipe, the gas bag is coaxial with the shaft body and keeps communication with the inside of the gas pipe, the gas pipe is connected with an external pneumatic system to supply or exhaust air to the gas bag, so that the gas bag expands or shrinks, the key strip is slidingly connected with the shaft body and is arranged at equal intervals along the circumference of the shaft body, the sliding direction of the key strip is perpendicular to the axial direction of the shaft body and is arranged at an angle with the radial direction of the shaft body; when the gas bag expands, the gas bag pushes the key strip to extend relative to the shaft body, and the key strip extrudes the gas bag to rotate along the circumference of the shaft body, when the gas bag shrinks, the key strip retracts relative to the shaft body.

[0007] Further, a reset spring coaxial with the shaft body and annular is arranged on the shaft body, the reset spring is in contact with the outer side of the key strip; when the gas bag expands, the key strip extrudes the reset spring to rotate along the circumference of the shaft body, when the gas bag shrinks, the reset spring makes the key strip retract relative to the shaft body.

[0008] Further, a plurality of moving parts are arranged at equal intervals along the axial direction of the shaft body, in adjacent two moving parts, the sliding directions of the two key strips relative to the shaft body are arranged at an angle, one of the gas bags can push the corresponding key strip to extend by a first distance, the other gas bag can push the corresponding key strip to extend by a second distance, the first distance is greater than the second distance; the roll is sleeved on the shaft body by an external force, and during the sleeving process, the gas bags are controlled to expand and shrink alternately by an external pneumatic system, when the gas bags expand, the key strips extending by the first distance contact and extrude the inner wall of the roll to rotate the roll along the circumference of the shaft body, the key strips extending by the second distance contact the inner wall of the roll.

[0009] Further, two gas path channels are formed in the gas pipe, adjacent two gas bags keep communication with the two gas path channels respectively, so that the expansion degrees of the adjacent two gas bags are the same or different.

[0010] Further, after the reel is sleeved on the shaft body by external force, the air bags are controlled to expand and contract alternately by an external pneumatic system, when the air bags expand, the key bar extending the first distance makes the reel continue to rotate along the circumferential direction of the shaft body, the key bar extending the first distance is provided with a sensor, the sensor is used for detecting the pressure value of the key bar along the sliding direction, when the change rate of the pressure value is less than a preset value within a preset time, the air bag corresponding to the key bar extending the first distance is kept expanding by the external pneumatic system.

[0011] Further, the moving part further comprises a sliding plate and a top plate, the key bar and the top plate are connected with two ends of the sliding plate respectively, the top plate abuts against the air bag, the shaft body is provided with a connecting piece capable of rotating, the rotation axis of the connecting piece is parallel to the axial direction of the shaft body, an elastic piece is arranged between the shaft body and the connecting piece, the elastic piece is used for resetting the connecting piece after the connecting piece rotates, and the sliding plate is in sliding connection with the connecting piece; when the reel is sleeved on the shaft body by external force, the key bar extending the second distance is in linear contact with the inner wall of the reel; when the reel is sleeved on the shaft body by external force and the pressure value is less than a preset value within a preset time, the air bag corresponding to the key bar extending the second distance is controlled to continue to expand by the external pneumatic system, so that the key bar extending the second distance contacts and extrudes the inner wall of the reel, and the key bar extending the second distance is in surface contact with the inner wall of the reel.

[0012] Further, the top plate is in the shape of a sector, the inner side of the top plate abuts against the air bag, and the outer side of the top plate is hinged to the sliding plate and the hinge shaft is parallel to the axial direction of the shaft body.

[0013] Further, the connecting piece is a cylinder body, the cylinder body is provided with a through hole for the sliding plate to slide through along the radial direction of the cylinder body.

[0014] Further, a first limiting piece is arranged between the air pipe and the air bag, when the key bar extrudes the air bag, the first limiting piece allows the air bag to rotate along the circumferential direction of the shaft body in the first rotation direction and restricts the air bag to rotate along the circumferential direction of the shaft body in the second rotation direction, and the first rotation direction is opposite to the second rotation direction.

[0015] Further, a second limiting piece is arranged between the shaft body and the reset spring, when the key bar extrudes the reset spring, the second limiting piece allows the reset spring to rotate along the circumferential direction of the shaft body in the second rotation direction and restricts the reset spring to rotate along the circumferential direction of the shaft body in the first rotation direction.

[0016] The present application has at least the following beneficial effects: (1) When the air bag expands, the key bar is pushed out relative to the shaft body, and because the sliding direction of the key bar is perpendicular to the axial direction of the shaft body and is arranged at an angle with the radial direction of the shaft body, the key bar exerts extrusion force on the air bag along the sliding direction, so that the air bag rotates by a certain angle along the circumferential direction of the shaft body, the contact position of the air bag and the key bar is switched in the circumferential direction, the air bag is uniformly pressed, plastic deformation (indentation) of the contact area of the air bag and the key bar is avoided, local stress concentration and uneven thickness of the air bag are relieved, the pressure resistance of the air bag is ensured, the risk of air bag rupture is reduced, material fatigue aging is slowed down, and the service life of the air bag is prolonged.

[0017] (2) When the air bag expands, the key bar is pushed out relative to the shaft body, and because the sliding direction of the key bar is perpendicular to the axial direction of the shaft body and is arranged at an angle with the radial direction of the shaft body, the key bar exerts extrusion force on the air bag along the sliding direction, so that the air bag rotates by a certain angle along the circumferential direction of the shaft body, the contact position of the air bag and the key bar is switched in the circumferential direction, the air bag is uniformly pressed, plastic deformation (indentation) of the contact area of the air bag and the key bar is avoided, local stress concentration and uneven thickness of the air bag are relieved, the pressure resistance of the air bag is ensured, the risk of air bag rupture is reduced, material fatigue aging is slowed down, and the service life of the air bag is prolonged.

[0018] (3) The winding drum is gradually sleeved on the shaft body in the axial direction of the shaft body through external force, and in the sleeving process, the air bag is controlled to expand and contract alternately through an external pneumatic system, when the air bag expands, the key bar extended by a first distance contacts and extrudes the inner wall of the winding drum, so that the winding drum rotates in a second rotation direction along the circumferential direction of the shaft body, and the key bar extended by a second distance only contacts the inner wall of the winding drum, so as to clean the burrs, burrs or dust attached to the inner wall of the winding drum, so that the inner wall of the winding drum tends to be flat, the stability of the contact between the winding drum and the key bar is improved, and the surface wear of the key bar is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The structure schematic view of the flexographic printing machine with adjustable tension of the paper feeding mechanism provided by the embodiment of the application is shown; Figure 2 The structure schematic view of the flexographic printing machine with adjustable tension of the paper feeding mechanism provided by the embodiment of the application is shown; Figure 1 The structure schematic view of the flexographic printing machine with adjustable tension of the paper feeding mechanism provided by the embodiment of the application is shown; Figure 3 The front view of the flexographic printing machine with adjustable tension of the paper feeding mechanism provided by the embodiment of the application is shown; Figure 2 The A-A cross-sectional view of the flexographic printing machine with adjustable tension of the paper feeding mechanism provided by the embodiment of the application is shown; Figure 4 Figure 3 The A-A cross-sectional view of the flexographic printing machine with adjustable tension of the paper feeding mechanism provided by the embodiment of the application is shown; Figure 5 The A-A cross-sectional view of the flexographic printing machine with adjustable tension of the paper feeding mechanism provided by the embodiment of the application is shown; Figure 4 The A-A cross-sectional view of the flexographic printing machine with adjustable tension of the paper feeding mechanism provided by the embodiment of the application is shown; Figure 6 Figure 4 The A-A cross-sectional view of the flexographic printing machine with adjustable tension of the paper feeding mechanism provided by the embodiment of the application is shown; Figure 7 The A-A cross-sectional view of the flexographic printing machine with adjustable tension of the paper feeding mechanism provided by the embodiment of the application is shown; Figure 6 The A-A cross-sectional view of the flexographic printing machine with adjustable tension of the paper feeding mechanism provided by the embodiment of the application is shown; Figure 8 Figure 3 The A-A cross-sectional view of the flexographic printing machine with adjustable tension of the paper feeding mechanism provided by the embodiment of the application is shown;​​​ Figure 9 F-F is a sectional view of the F-F; Figure 3 Figure 10 F-F is a sectional view of the F-F; Figure 9 F-F is a sectional view of the F-F; Figure 11 F-F is a sectional view of the F-F;

[0020] Wherein: 100, body; 101, shaft; 102, air pipe; 103, air bag; 104, key bar; 105, roller; 106, reset spring; 107, reel; 201, support ring; 202, fixed ring; 203, first side hole; 204, first ring groove; 205, second side hole; 206, second ring groove; 207, sealing ring; 208, air path channel; 209, sliding plate; 210, top plate; 211, connecting piece; 212, elastic piece; 213, first limiting piece; 214, second limiting piece. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below with examples and in conjunction with the drawings. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0022] The numbers of components in this paper, such as "first", "second", etc., are only used to distinguish the described objects, and do not have any order or technical meaning. The "connection" and "coupling" of the present application include direct and indirect connection (coupling) unless otherwise specified. In the description of the present application, it should be understood that the orientation or position relationship indicated by the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0023] ​In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature is "above", "over" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature. The first feature is "below", "under" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is horizontally lower than the second feature.

[0024] As shown in Figures 1 to 11 The embodiment of the present application provides a paper feeding mechanism with adjustable tension for a flexographic printing machine, which comprises a machine body 100 and a shaft body 101 rotatably arranged on the machine body 100 and used for supporting a roller 107, a shaft cavity is formed in the shaft body 101, a gas pipe 102 coaxial with the shaft body 101 is arranged in the shaft cavity, a moving part is arranged on the gas pipe 102, the moving part comprises a gas bag 103 and a key strip 104, the gas bag 103 is annular and rotationally connected with the gas pipe 102, the gas bag 103 is coaxial with the shaft body 101 and keeps communication with the inside of the gas pipe 102, the gas pipe 102 is connected with an external pneumatic system to supply or exhaust air to the gas bag 103, so that the gas bag 103 expands or shrinks, the key strip 104 is slidingly connected with the shaft body 101 and is arranged at equal intervals along the circumference of the shaft body 101, and the sliding direction of the key strip 104 is perpendicular to the axial direction of the shaft body 101 and is arranged at an angle with the radial direction of the shaft body 101; when the gas bag 103 expands, the gas bag 103 pushes the key strip 104 to extend relative to the shaft body 101, and the key strip 104 extrudes the gas bag 103, so that the gas bag 103 rotates along the circumference of the shaft body 101, and when the gas bag 103 shrinks, the key strip 104 retracts relative to the shaft body 101.

[0025] When the gas bag 103 expands, the gas bag 103 pushes the key strip 104 to extend relative to the shaft body 101, since the sliding direction of the key strip 104 is perpendicular to the axial direction of the shaft body 101 and is arranged at an angle with the radial direction of the shaft body 101, the key strip 104 extrudes the gas bag 103 along the sliding direction, so that the gas bag 103 rotates by a certain angle along the circumference of the shaft body 101, the contact position of the gas bag 103 and the key strip 104 is switched in the circumferential direction, the gas bag 103 is uniformly extruded, plastic deformation (indentation) of the contact area of the gas bag 103 and the key strip 104 is avoided, local stress concentration and uneven thickness of the gas bag 103 are relieved, the pressure resistance of the gas bag 103 is ensured, the risk of rupture of the gas bag 103 is reduced, material fatigue aging is slowed down, and the service life of the gas bag 103 is prolonged.

[0026] Specifically, the airbag 103 is annular and expands and contracts primarily along the radial direction of the shaft 101 to facilitate the pushing action of the key bar 104. A keyway can be formed on the shaft 101, through which the key bar 104 can extend or retract. Multiple rotatable rollers 105 are provided on the shaft 101 along its circumference and axial direction. The rotation axis of the rollers 105 is tangential to the shaft 101. When the drum 107 is fitted onto the shaft 101 by external force, the rollers 105 support and guide the drum 107. The shaft 101 is made of high-stress steel or aluminum alloy and is driven to rotate by an external power source. The end of the shaft 101 is rotatably mounted at the feed port of the machine body 100. The key bar 104 is chrome-plated / nickel-plated to enhance wear resistance and is compatible with various types of drums 107 (paper tubes, plastic film cores, etc.).

[0027] Existing flexographic printing presses may include a body 100 and, mounted on the body 100, an unwinding and rewinding mechanism, both of which use a shaft 101 to clamp the roll 107 and use an airbag 103 to control the extension and retraction of the key bar 104 to ensure rapid roll changing and tension control for paper feeding or take-up; a printing mechanism, typically arranged by color group, with each unit containing an ink fountain, ink fountain roller, an anilox roller, a printing plate cylinder, and an impression cylinder; a drying mechanism, located between or at the end of the color groups, which cures the ink using hot air or UV; and a transmission and control system, including a motor, a tension sensor, and a registration adjustment device. During operation, ink is transferred from the ink fountain roller to the anilox roller, which evenly coats the ink onto the raised image portion of the printing plate cylinder. As the substrate passes between the impression cylinder and the printing plate cylinder, image transfer is completed under pressure. The material then passes through the drying mechanism to cure the ink and is finally rewound by the rewinding mechanism. The external pneumatic system may include: an air source device, including an air compressor, an air tank, and purification equipment, responsible for providing stable and clean compressed air; and control elements, including valves and other components. The valves are used to control the gas flow direction and flow rate, enabling rapid switching and precise adjustment of the expansion and contraction of the airbag 103. The above-mentioned flexographic printing press and the external pneumatic system's structure, composition, and working principle are all prior art, and this application will not elaborate on them.

[0028] In one embodiment, a return spring 106 is provided on the shaft 101 and is coaxial with it and in a ring shape. The return spring 106 contacts the outer side of the key bar 104. When the airbag 103 inflates, the key bar 104 squeezes the return spring 106, causing the return spring 106 to rotate circumferentially along the shaft 101. When the airbag 103 contracts, the return spring 106 causes the key bar 104 to retract relative to the shaft 101.

[0029] In existing pneumatic shafts, the return spring 106 of the key bar 104 is fixed relative to the shaft body 101. After long-term use, the force and deformation of the return spring 106 become uneven, resulting in insufficient restoring force and causing the key bar 104 to have difficulty returning to its original position. In this application, when the airbag 103 inflates, it pushes the key bar 104 to extend relative to the shaft body 101. Since the sliding direction of the key bar 104 is perpendicular to the axial direction of the shaft body 101 and forms an angle with the radial direction of the shaft body 101, the key bar 104 applies a compressive force to the return spring 106 along its sliding direction, causing the return spring 106 to rotate a certain angle around the circumference of the shaft body 101. This allows the contact position between the return spring 106 and the key bar 104 to be switched circumferentially, ensuring uniform force and deformation of the return spring 106 and guaranteeing its restoring force, thereby alleviating the problem of the key bar 104 not returning to its original position smoothly.

[0030] Specifically, an annular mounting groove can be provided on the shaft 101 for mounting a ring-shaped return spring 106. In the axial direction of the shaft 101, the return spring 106 is located in the middle of the key bar 104 to apply a stable restoring force to the key bar 104 when the airbag 103 contracts.

[0031] It is understandable that, since the sliding direction of the key bar 104 is perpendicular to the axial direction of the shaft 101 and forms an angle with the radial direction of the shaft 101, for the airbag 103, the key bar 104 applies a compressive force to the airbag 103 along its sliding direction, causing the airbag 103 to rotate a certain angle around the circumference of the shaft 101. For the return spring 106, the key bar 104 applies a compressive force to the return spring 106 along its sliding direction, causing the return spring 106 to rotate a certain angle around the circumference of the shaft 101, and the direction of rotation of the airbag 103 is opposite to the direction of rotation of the return spring 106.

[0032] In one embodiment, multiple moving parts are equally spaced along the axial direction of the shaft 101. In two adjacent moving parts, two key bars 104 are arranged at an angle relative to the sliding direction of the shaft 101. One airbag 103 can push its corresponding key bar 104 to extend a first distance, and the other airbag 103 can push its corresponding key bar 104 to extend a second distance. The first distance is greater than the second distance. The drum 107 is fitted onto the shaft 101 by external force. During the fitting process, the airbag 103 is controlled by an external pneumatic system to alternately expand and contract. When the airbag 103 expands, the key bar 104 extending a first distance contacts and squeezes the inner wall of the drum 107, so that the drum 107 rotates circumferentially along the shaft 101. The key bar 104 extending a second distance contacts the inner wall of the drum 107.

[0033] The existing drum 107, due to its high usage frequency, may develop burrs, flakes, or dust on its inner wall, resulting in an uneven inner wall that reduces the stability of its contact with the key bar 104 and exacerbates surface wear on the key bar 104. In this application, the drum 107 is gradually fitted onto the shaft 101 axially using external force. During the fitting process, an external pneumatic system controls the airbag 103 to alternately expand and contract. When the airbag 103 expands, the key bar 104 extending a first distance contacts and presses against the inner wall of the drum 107, causing the drum 107 to rotate circumferentially along the shaft 101. Meanwhile, the key bar 104 extending a second distance contacts and scrapes against the inner wall of the drum 107. This cycle cleans the burrs, flakes, or dust from the inner wall of the drum 107, making the inner wall of the drum 107 smoother, improving the stability of its contact with the key bar 104, and reducing surface wear on the key bar 104.

[0034] Specifically, see Figures 4 to 7 The air tube 102 is provided with a support ring 201 that rotates via a bearing. Correspondingly, the number of support rings 201 is the same as that of the moving parts. The annular airbag 103 is provided with two fixing rings 202. The outer wall of the support ring 201 is formed with annular grooves. The fixing rings 202 are used to press the ends of the airbag 103 into the annular grooves to achieve fixation and sealing of both ends of the airbag 103. An air passage 208 is formed inside the trachea 102. A first side hole 203 is formed radially on the trachea 102. A first annular groove 204 is formed on the outer wall of the trachea 102. The air passage 208, the first side hole 203, and the first annular groove 204 are connected in sequence. A second side hole 205 is formed radially on the support ring 201. A second annular groove 206 is formed on the outer wall of the support ring 201. The second side hole 205, the second annular groove 206, and the airbag 103 are connected in sequence. Therefore, the gas in the air passage 208 flows sequentially through the first side hole 203, the first annular groove 204, the second side hole 205, and the second annular groove 206 to the airbag 103, causing the airbag 103 to inflate. The gas in the airbag 103 flows sequentially through the second annular groove 206, the second side hole 205, the first annular groove 204, and the first side hole 203 to the air passage 208, causing the airbag 103 to contract. In addition, a sealing ring 207 is provided between the air tube 102 and the support ring 201. Two sealing rings 207 are provided and are located on both sides of the first annular groove 204 respectively to ensure the sealing performance when the gas flows between the first annular groove 204 and the second side hole 205. For the support rings 201 located at both ends, one end is sealed and the other end is open, and they are rotatably connected to the shaft 101 through bearings. For the support ring 201 in the middle, both ends are open and are rotatably connected to the shaft 101 through bearings.

[0035] Understandably, in the circumferential direction of the shaft 101, i.e., for a single moving part, the sliding direction of each key bar 104 is inclined to the same side relative to the radial direction of the shaft 101, forming a unidirectional cyclone-like shape. For adjacent moving parts, all key bars 104 form opposite unidirectional cyclone shapes. However, in the axial direction of the shaft 101, i.e., for two adjacent moving parts, the sliding directions of the two key bars 104 are inclined to opposite sides relative to the radial direction of the shaft 101, i.e., the sliding directions of the two key bars 104 are set at an angle. Therefore, for two adjacent moving parts, the airbag 103 and the return spring 106 rotate in opposite directions. Furthermore, when the drum 107 is fitted onto the shaft 101 by external force, this external force can be generated by the drive mechanism located on the body 100, which can precisely push the new drum 107 along the axial direction of the shaft 101 without manual intervention.

[0036] It is understandable that, since the sliding direction of the key bar 104 is perpendicular to the axial direction of the shaft 101 and forms an angle with the radial direction of the shaft 101, for the return spring 106, the key bar 104 applies a compressive force to the return spring 106 along its sliding direction, causing the return spring 106 to rotate a certain angle around the circumference of the shaft 101. For the drum 107, the key bar 104 applies a compressive force to the drum 107 along its sliding direction, causing the drum 107 to rotate a certain angle around the circumference of the shaft 101, and the direction of rotation of the return spring 106 is the same as the direction of rotation of the drum 107.

[0037] In one embodiment, two air passages 208 are formed in the trachea 102, and two adjacent airbags 103 are respectively connected to the two air passages 208 so that the two adjacent airbags 103 have the same or different degree of inflation.

[0038] The two air passages 208 supply air to the two airbags 103 respectively, which can make the two adjacent airbags 103 expand to different degrees, thereby pushing the corresponding two key bars 104 to extend different distances.

[0039] Specifically, the two air passages 208 are respectively connected to two external pneumatic systems to independently control parameters such as the air supply volume and air supply speed within the two air passages 208, thereby enabling adjacent airbags 103 to expand to the same or different degrees. Furthermore, adjacent airbags 103 are respectively connected to the two air passages 208, for example, as... Figure 4 and Figure 5 As shown, one air passage 208 is connected to the airbags 103 corresponding to the first, third and fifth moving parts, and the other air passage 208 is connected to the airbags 103 corresponding to the second, fourth and sixth moving parts.

[0040] In one embodiment, after the drum 107 is fitted onto the shaft 101 by external force, the airbag 103 is alternately expanded and contracted by an external pneumatic system. When the airbag 103 expands, the key bar 104 extending a first distance causes the drum 107 to continue rotating circumferentially along the shaft 101. A sensor is provided on the key bar 104 extending a first distance. The sensor is used to detect the pressure value of the key bar 104 along its sliding direction. When the rate of change of the pressure value is less than the preset value within a preset time, the airbag 103 corresponding to the key bar 104 extending a first distance is kept expanded by the external pneumatic system.

[0041] The existing drum 107 is relatively heavy, which can easily cause indentations on the inner wall of the drum 107, reduce the stability of its contact with the key bar 104, and affect the coaxiality of the drum 107 and the shaft 101, which may lead to unstable tension during unwinding. In this application, the intermittently extending key bar 104 can support the drum 107, reducing the indentations on the inner wall of the drum 107. At the same time, the pressure value of the key bar 104 along its sliding direction is detected by the sensor. The rate of change of the pressure value reflects the flatness of the inner wall of the drum 107. The greater the rate of change of the pressure value, the more uneven the inner wall of the drum 107. When the rate of change of the pressure value is less than the preset value within a preset time, it indicates that the pressure value fluctuation is small and the inner wall of the drum 107 is relatively flat. At this time, the air bladder 103 corresponding to the key bar 104 extending a first distance can be controlled by the external pneumatic system to keep it inflated. The key bar 104 extending a first distance provides final support for the drum 107. The contact between the drum 107 and the key bar 104 is stable, ensuring the coaxiality of the drum 107 and the shaft 101, thereby making the tension more stable during unwinding.

[0042] Specifically, the machine body 100 may also be equipped with a processor. The sensor sends the detected pressure value to the processor. The processor calculates the rate of change of the pressure value and compares it with the preset value in real time. If the rate of change of the pressure value is less than the preset value within a preset time, such as 5 seconds, it indicates that the pressure value fluctuates less and the inner wall of the drum 107 is relatively flat at the current position. At this time, the processor controls the air bag 103 corresponding to the key bar 104 that extends a first distance to keep inflated through the external pneumatic system. The key bar 104 that extends a first distance provides final support for the drum 107.

[0043] In one embodiment, the moving part further includes a slide plate 209 and a top plate 210. The key bar 104 and the top plate 210 are respectively connected to both ends of the slide plate 209. The top plate 210 abuts against the airbag 103. A rotatable connector 211 is provided on the shaft 101. The rotation axis of the connector 211 is parallel to the axial direction of the shaft 101. An elastic member 212 is provided between the shaft 101 and the connector 211. The elastic member 212 is used to reset the connector 211 after rotation. The slide plate 209 is slidably connected to the connector 211. When the drum 107 is fitted onto the shaft 101 by external force, the key bar 104 extending a second distance contacts the inner wall of the drum 107. After the drum 107 is fitted onto the shaft 101 by external force, and the pressure value is less than the preset value within a preset time, the air bladder 103 corresponding to the key bar 104 extending a second distance is controlled by the external pneumatic system to continue to expand, so that the key bar 104 extending a second distance contacts and squeezes the inner wall of the drum 107, and the key bar 104 extending a second distance contacts the inner wall surface of the drum 107.

[0044] When the drum 107 is fitted onto the shaft 101, the key bar 104 extending a second distance, which serves a cleaning function, makes line contact with the inner wall of the drum 107, reducing wear on the key bar 104. After the drum 107 is fitted onto the shaft 101, and the pressure value is less than the preset value within a preset time, the key bar 104 extending a first distance, which serves a supporting function, provides final support to the drum 107. The air bladder 103 corresponding to the key bar 104 extending a second distance is controlled by the external pneumatic system to continue to expand, causing the key bar 104 extending a second distance to contact and squeeze the inner wall of the drum 107. At this time, all the key bars 104 provide effective support for the drum 107, and the key bar 104 extending a second distance contacts the inner wall surface of the drum 107, ensuring the stability of the contact between the key bar 104 and the inner wall of the drum 107.

[0045] When the top plate 210, slide plate 209 and key bar 104 are extended by the pushing force of the airbag 103 expansion, the slide plate 209 and key bar 104 can also rotate relative to the shaft 101 through the connector 211, so that the key bar 104 extending a second distance switches between line contact and surface contact with the inner wall of the drum 107.

[0046] Specifically, such as Figure 10 As shown, the key bar 104 has a first arc surface and a second arc surface on the side away from the axis of the shaft 101. The radius of the first arc surface is smaller than or much smaller than the radius of the second arc surface, and the radius of the second arc surface is equal to the inner radius of the drum 107, so that when the first arc surface contacts the inner wall of the drum 107, it is a line contact, and when the second arc surface contacts the inner wall of the drum 107, it is a surface contact.

[0047] It is understandable that, since the airbag 103 corresponding to the key bar 104 extending the first distance has a large degree of expansion, when the drum 107 is fitted onto the shaft 101 by external force, the key bar 104 extending the first distance is in surface contact with the inner wall of the drum 107, so as to ensure the contact stability between the key bar 104 extending the first distance and the inner wall of the drum 107.

[0048] In one embodiment, the top plate 210 has a fan-shaped cross-section, the inner side of the top plate 210 abuts against the airbag 103, and the outer side of the top plate 210 is hinged to the slide plate 209 with the hinge axis (not shown) parallel to the axial direction of the shaft 101.

[0049] Increasing the contact area between the top plate 210 and the airbag 103 reduces stress concentration on the airbag 103. Simultaneously, the top plate 210 is hinged to the slide plate 209. When the top plate 210, slide plate 209, and key bar 104 extend under the pushing force of the inflated airbag 103, and the slide plate 209 and key bar 104 can also rotate relative to the shaft 101 via the connecting piece 211, the slide plate 209 and key bar 104 can also rotate relative to the top plate 210, thus avoiding motion interference.

[0050] In one embodiment, the connector 211 is a cylindrical body with its axis parallel to the axis of the shaft 101, and the cylindrical body has a through hole in its radial direction for the sliding plate 209 to slide through.

[0051] The elastic element 212 is a spring, and multiple springs can be provided and located between the cylinder and the shaft 101.

[0052] In one embodiment, see Figure 9 A first limiting member 213 is provided between the trachea 102 and the airbag 103. When the key bar 104 squeezes the airbag 103, the first limiting member 213 allows the airbag 103 to rotate in a first direction along the circumference of the shaft 101, and restricts the airbag 103 from rotating in a second direction along the circumference of the shaft 101. The first direction and the second direction are opposite.

[0053] When the key bar 104 compresses the airbag 103 in the first direction, the first limiting member 213 makes the airbag 103 only rotate in one direction along the circumference of the shaft 101, so as to more effectively switch the contact position between the airbag 103 and the key bar 104 in the circumference, so that the airbag 103 is evenly compressed.

[0054] Specifically, the first limiting member 213 may be made of a soft material, and includes a ring body and a plurality of oblique teeth evenly spaced along the circumference of the ring body. The first limiting member 213 allows the airbag 103 to rotate with the support ring 201 in the direction of the oblique teeth, that is, to rotate in a first direction along the circumference of the shaft body 101. The first limiting member 213 restricts the airbag 103 from rotating with the support ring 201 in the opposite direction of the oblique teeth, that is, to rotate in a second direction along the circumference of the shaft body 101.

[0055] In one embodiment, see Figure 11 A second limiting member 214 is provided between the shaft 101 and the return spring 106. When the key bar 104 presses the return spring 106, the second limiting member 214 allows the return spring 106 to rotate in a second direction along the circumference of the shaft 101, and restricts the return spring 106 from rotating in a first direction along the circumference of the shaft 101.

[0056] When the key bar 104 presses the return spring 106, the second limiting member 214 makes the return spring 106 only rotate in one direction along the circumference of the shaft 101, so as to more effectively switch the contact position between the return spring 106 and the key bar 104 in the circumference, and make the return spring 106 subjected to force and deformation uniform.

[0057] Specifically, the second limiting member 214 may be made of a soft material and includes a ring body and a plurality of helical teeth evenly spaced along the circumference of the ring body. The second limiting member 214 allows the return spring 106 to rotate in the direction of the helical teeth, that is, to rotate in a second direction along the circumference of the shaft 101. The second limiting member 214 restricts the return spring 106 from rotating in the opposite direction of the helical teeth, that is, to rotate in a first direction along the circumference of the shaft 101.

[0058] The working process of this invention is as follows: The drum 107 is gradually fitted onto the shaft 101 along the axial direction by external force, and the drum 107 is guided by the roller 105. During the fitting process, the airbag 103 is alternately expanded and contracted by the external pneumatic system. When the airbag 103 expands, the key bar 104 extending a first distance contacts and squeezes the inner wall of the drum 107, so that the drum 107 rotates in a second direction along the circumference of the shaft 101. Meanwhile, the key bar 104 extending a second distance contacts and scrapes the inner wall of the drum 107. This cycle is repeated to clean the burrs, rough edges, or dust adhering to the inner wall of the drum 107, thereby making the inner wall of the drum 107 more flat, improving the stability of its contact with the key bar 104, and reducing the wear on the surface of the key bar 104.

[0059] After the drum 107 is fitted onto the shaft 101 by external force, the air bladder 103 continues to expand and contract alternately under the control of the external pneumatic system. The intermittently extended key bar 104 can support the drum 107 and reduce the pressure marks on the inner wall of the drum 107. At the same time, the pressure value on the key bar 104 along its sliding direction is detected by the sensor. The rate of change of the pressure value reflects the flatness of the inner wall of the drum 107. The greater the rate of change of the pressure value, the more uneven the inner wall of the drum 107 is. When the rate of change of the pressure value is less than the preset value within a preset time, it means that the pressure value fluctuation is small and the inner wall of the drum 107 is relatively flat. At this time, the air bladder 103 corresponding to the key bar 104 extending a first distance can be controlled by the external pneumatic system to keep expanding. The key bar 104 extending a first distance provides final support for the drum 107. The contact between the drum 107 and the key bar 104 is stable, ensuring the coaxiality of the drum 107 and the shaft 101, thereby making the tension more stable during unwinding.

[0060] During each inflation of the airbag 103, the airbag 103 pushes the key bar 104 to extend relative to the shaft 101. Since the sliding direction of the key bar 104 is perpendicular to the axial direction of the shaft 101 and forms an angle with the radial direction of the shaft 101, the key bar 104 applies a compressive force to the airbag 103 along its sliding direction, causing the airbag 103 to rotate a certain angle around the circumference of the shaft 101. This allows the contact position between the airbag 103 and the key bar 104 to be switched in the circumferential direction, ensuring that the airbag 103 is evenly compressed. This prevents plastic deformation (indentation) in the contact area with the key bar 104, alleviates the problem of local stress concentration and uneven thickness of the airbag 103, ensures the pressure resistance of the airbag 103, reduces the risk of airbag 103 rupture, and slows down material fatigue aging, thus extending the service life of the airbag 103. At the same time, when the airbag 103 pushes the key bar 104 to extend relative to the shaft 101, the key bar 104 can also apply a squeezing force to the return spring 106 along its sliding direction, causing the return spring 106 to rotate a certain angle along the circumference of the shaft 101, so as to switch the contact position between the return spring 106 and the key bar 104 in the circumferential direction, so that the return spring 106 is subjected to force and deformation evenly, ensuring the restoring force of the return spring 106, thereby reducing the problem of the key bar 104 not resetting smoothly.

[0061] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0062] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A paper feeding mechanism for a tension-adjustable flexographic printing press, characterized in that, The device includes a shaft for supporting a drum, a shaft cavity formed within the shaft, an air tube coaxial with the shaft within the shaft cavity, a moving part on the air tube, the moving part including an air bladder and key bars, the air bladder being annular and rotatably connected to the air tube, the air bladder being coaxial with the shaft and communicating with the interior of the air tube, the air tube being connected to an external pneumatic system to supply or evacuate the air bladder, causing the air bladder to expand or contract, and the key bars being slidably connected to the shaft and multiple key bars being evenly spaced along the circumference of the shaft, the sliding direction of the key bars being perpendicular to the axial direction of the shaft and forming an angle with the radial direction of the shaft; When the airbag inflates, the airbag pushes the key bar to extend relative to the shaft, and the key bar squeezes the airbag, causing the airbag to rotate circumferentially along the shaft. When the airbag contracts, the key bar retracts relative to the shaft.

2. The tension-adjustable paper feeding mechanism for a flexographic printing press according to claim 1, characterized in that, The shaft is provided with a return spring that is coaxial with it and in a ring shape. The return spring is in contact with the outer side of the key bar. When the airbag inflates, the key bar squeezes the return spring, causing the return spring to rotate around the circumference of the shaft. When the airbag contracts, the return spring causes the key bar to retract relative to the shaft.

3. The tension-adjustable paper feeding mechanism for a flexographic printing press according to claim 2, characterized in that, Multiple moving parts are equally spaced along the axial direction of the shaft. In two adjacent moving parts, the two key bars are arranged at an angle relative to the sliding direction of the shaft. One airbag can push the corresponding key bar to extend out a first distance, and the other airbag can push the corresponding key bar to extend out a second distance. The first distance is greater than the second distance. The spool is fitted onto the shaft by external force, and during the fitting process, the airbag is alternately expanded and contracted by an external pneumatic system. When the airbag expands, the key bar extending from the first distance contacts and squeezes the inner wall of the spool, so that the spool rotates circumferentially along the shaft. The key bar extending from the second distance contacts the inner wall of the spool.

4. The tension-adjustable paper feeding mechanism for a flexographic printing press according to claim 3, characterized in that, Two air passages are formed within the trachea, and two adjacent airbags are respectively connected to the two air passages so that the two adjacent airbags inflate to the same degree or with different degrees.

5. The tension-adjustable paper feeding mechanism for a flexographic printing press according to claim 4, characterized in that, After the drum is fitted onto the shaft by external force, the airbag is alternately expanded and contracted by an external pneumatic system. When the airbag expands, the key bar that extends the first distance causes the drum to continue rotating around the circumference of the shaft. A sensor is provided on the key bar extending beyond the first distance. The sensor is used to detect the pressure value of the key bar along its sliding direction. When the rate of change of the pressure value is less than a preset value within a preset time, the air bladder corresponding to the key bar extending beyond the first distance is controlled by an external pneumatic system to keep it inflated.

6. The tension-adjustable paper feeding mechanism for a flexographic printing press according to claim 5, characterized in that, The moving part also includes a sliding plate and a top plate. The key bar and the top plate are respectively connected to both ends of the sliding plate. The top plate abuts against the airbag. A rotatable connector is provided on the shaft. The rotation axis of the connector is parallel to the axial direction of the shaft. An elastic element is provided between the shaft and the connector. The elastic element is used to reset the connector after rotation. The sliding plate is slidably connected to the connector. When the spool is fitted onto the shaft by external force, the key bar extending at the second distance contacts the inner wall line of the spool. After the spool is fitted onto the shaft by external force, and the pressure value is less than the preset value within a preset time, the airbag corresponding to the key bar extending the second distance is controlled by the external pneumatic system to continue to expand, so that the key bar extending the second distance contacts and squeezes the inner wall of the spool, and the key bar extending the second distance contacts the inner wall surface of the spool.

7. The tension-adjustable paper feeding mechanism for a flexographic printing press according to claim 6, characterized in that, The top plate has a fan-shaped cross-section. The inner side of the top plate abuts against the airbag, and the outer side of the top plate is hinged to the sliding plate with the hinge axis parallel to the axial direction of the shaft.

8. The tension-adjustable paper feeding mechanism for a flexographic printing press according to claim 6, characterized in that, The connector is a cylindrical body with its axis parallel to the axial direction of the shaft. The cylindrical body has a through hole along its radial direction for the sliding plate to slide through.

9. The tension-adjustable paper feeding mechanism for a flexographic printing press according to claim 2, characterized in that, A first limiting member is provided between the trachea and the airbag. When the key bar squeezes the airbag, the first limiting member allows the airbag to rotate in the first direction of rotation along the circumference of the shaft, and restricts the airbag from rotating in the second direction of rotation along the circumference of the shaft. The first direction of rotation is opposite to the second direction of rotation.

10. The tension-adjustable paper feeding mechanism for a flexographic printing press according to claim 9, characterized in that, A second limiting member is provided between the shaft and the return spring. When the key bar presses the return spring, the second limiting member allows the return spring to rotate in the second direction along the circumference of the shaft, and restricts the return spring from rotating in the first direction along the circumference of the shaft.

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