Paper positioning device for flat sheet printing machine

Abstract

The invention belongs to the technical field of flat sheet printing equipment, and particularly relates to a paper positioning device for a flat sheet printing machine. The positioning table plate is fixed to the supporting frame, a first strip-shaped opening and two second strip-shaped openings which are parallel to each other are formed in the positioning table plate, supporting plates are installed in the two second strip-shaped openings in a sliding mode, and a second positioning plate is installed in the first strip-shaped opening in a sliding mode; the two positioning plates I are fixedly mounted on the top sides of the corresponding supporting plates respectively; the mounting box is arranged on the bottom side of the supporting frame; the distance adjusting assembly is arranged on the mounting box and connected with the two supporting plates; the linkage assembly is arranged on the distance adjusting assembly and connected with the second positioning plate. The whole structural design is reasonable, operation and maintenance are convenient, good adaptability to positioning of paper of different specifications and thicknesses is achieved, meanwhile, the influence of curling and self-stress of the paper on the paper positioning precision can be effectively eliminated, and therefore the diversified printing production requirements can be met.

Description

Technical Field

[0001] This invention relates to the field of sheet-fed printing equipment technology, and in particular to a paper positioning device for sheet-fed printing presses. Background Technology

[0002] In sheet printing, precise paper positioning is crucial for ensuring print quality. Traditional paper positioning devices often cause paper to be squeezed and deformed when adjusting the positioning of individual sheets.

[0003] The existing Chinese patent document with authorization announcement number CN218753861U discloses a high-precision paper positioning mechanism for printing presses. Its core positioning structure is a combination of positioning roller, moving frame and guide roller. At the same time, a motor drives a double lead screw to drive the moving frame to control the positioning roller to limit the paper position.

[0004] The existing Chinese patent document with authorization announcement number CN219906259U discloses a high-precision paper positioning mechanism for printing presses. Its core positioning mechanism is a combination of U-shaped seat, support roller, limiting plate and gear. At the same time, it achieves paper positioning by driving the limiting plate to slide through the gear and by using a flattening mechanism.

[0005] However, the existing technologies represented by the aforementioned patents still have the following technical problems: In the process of sheet printing, the precise positioning of the paper is generally only done from the front and back sides of the paper conveying direction to prevent it from deviating. At the same time, the adjustment is mostly done by independent drive. In practical applications, it is easy to fail to effectively position the paper that may have warping and internal stress. Furthermore, it does not have the ability to effectively eliminate the warping and internal stress that may exist in the paper, which will affect the final printing effect.

[0006] Therefore, the present invention proposes a paper positioning device for a sheet-fed printing press to solve the above problems. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing a paper positioning device for sheet-fed printing presses.

[0008] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a paper positioning device for a sheet-fed printing press, comprising:

[0009] Support frame;

[0010] A positioning platform is fixed on a support frame, and the positioning platform has a first strip opening and two second strip openings arranged in parallel. A support plate is slidably installed in each of the two second strip openings, and a positioning plate is slidably installed in the first strip opening.

[0011] Two positioning plates are fixedly installed on the top side of the corresponding support plate;

[0012] The mounting box is located on the bottom side of the support frame;

[0013] The spacing adjustment component is mounted on the mounting box and connected to the two support plates;

[0014] The linkage component is mounted on the spacing adjustment component and connected to the positioning plate.

[0015] Multiple contact sensors are fixedly installed on one side of two positioning plates that are close to each other;

[0016] The blowing component is located above the support frame. It can blow and position the paper on the positioning platform.

[0017] A photoelectric sensor, mounted on the blowing assembly, is used to detect whether there is paper on the positioning platform.

[0018] Preferably, the spacing adjustment assembly includes a servo motor, a transmission gear, and two toothed plates. Two toothed plates are slidably mounted on the mounting box, and the two toothed plates are respectively fixedly connected to the corresponding support plates. A servo motor is fixedly mounted on one side of the mounting box, and a rotating shaft is connected to the output shaft of the servo motor. A transmission gear that meshes with the two toothed plates is fixedly sleeved on the rotating shaft.

[0019] Preferably, the linkage assembly includes a support rod, a guide pin, and a lifting plate. The bottom side of the positioning plate is fixedly installed with a lifting plate that slides in contact with the inner walls of the front and rear sides of the mounting box. A guide groove is provided on the lifting plate. The end of the rotating shaft is radially fixedly installed with a support rod, and a guide pin is radially fixedly installed on the support rod. The guide pin is slidably installed in the guide groove.

[0020] Preferably, the blowing assembly includes a hollow plate, a variable frequency fan, and multiple air holes. Four support columns are fixedly installed on the support frame, and a hollow plate is fixedly installed on the top of the four support columns. The variable frequency fan is fixedly installed on the top side of the hollow plate, and the air outlet of the variable frequency fan is connected to the hollow plate. Multiple air holes are arranged in a circular array with the midpoint of the top side of the positioning platform as the center on the bottom inner wall of the hollow plate, and a photoelectric sensor is fixedly installed on the bottom side of the hollow plate.

[0021] Preferably, the angle between the axis of the multiple air holes and the axis of the midpoint of the top side of the positioning platform increases from the inside to the outside, and the tilt angle of the multiple air holes other than the air hole at the center position is within the range of 15-30 degrees.

[0022] Preferably, a through hole is provided at the midpoint of the top side of the positioning platform, and multiple radially arranged air guide grooves are provided on the top side of the positioning platform with the through hole as the center.

[0023] Preferably, a fixing plate is fixedly installed inside the mounting box, and an installation opening is provided on the fixing plate. A bearing is fixedly installed inside the installation opening, and the inner ring of the bearing is fixedly sleeved on the outside of the rotating shaft.

[0024] Preferably, both the second positioning plate and the lifting plate have cavities on the side away from the first positioning plate.

[0025] Preferably, elastic buffer pads are fixedly installed on the sides of the two positioning plates that are close to each other. The thickness of the elastic buffer pads is 3-5mm, and multiple contact sensors are embedded and fixed in the elastic buffer pads on the corresponding sides.

[0026] Preferably, strip plates are fixedly installed on both sides of the top of the mounting box, and each strip plate is fixed to the bottom side of the support frame by at least two bolts.

[0027] The beneficial effects of this invention are:

[0028] This invention, through the cooperation of the servo motor, transmission gear, and two toothed plates in the spacing adjustment component, can precisely adjust the spacing between the two positioning plates. Combined with the contact sensors on them, it can achieve precise positioning from both the front and rear sides of the paper, effectively avoiding the problem of paper deformation due to compression in traditional positioning methods. Simultaneously, the linkage component utilizes the support rod and guide pin at the end of the rotating shaft to adjust the spacing of the positioning plates while simultaneously driving the lifting plate via the guide groove to adjust the height of the second positioning plate. This achieves linkage control between the two positioning plates, simplifying the operation process, reducing independent drive components, significantly improving the synchronization and stability of the device's operation, and ensuring the accuracy of positioning adjustment.

[0029] In addition, through the coordination of the blowing components, air can be delivered into the hollow plate by the variable frequency fan, and the airflow is formed by multiple blowing holes arranged at specific angles and in an array, which can effectively counteract the warping and internal stress of the paper. Combined with the air guide groove on the positioning plate, the paper can be prevented from being blown up by the airflow, ensuring that the paper is positioned by positioning plate one and positioning plate two in a flat state, further improving the positioning accuracy. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a three-dimensional structural schematic diagram of a paper positioning device for a sheet printing press proposed in this invention;

[0032] Figure 2 for Figure 1 A schematic diagram of the cross-sectional structure;

[0033] Figure 3 This is a partial three-dimensional structural diagram of the present invention;

[0034] Figure 4 This is a schematic diagram of the structure of the support frame, positioning platform, slot one, slot two, through hole and air guide groove proposed in this invention;

[0035] Figure 5 This is a structural schematic diagram of the mounting box, support plate, and strip plate components proposed in this invention;

[0036] Figure 6 This is a schematic diagram of the structure of the support column, air hole, hollow plate and photoelectric sensor part proposed in this invention;

[0037] Figure 7 This is a three-dimensional structural diagram of the positioning plate 2 and the lifting plate part proposed in this invention.

[0038] In the diagram: 1. Support frame; 11. Positioning platform; 111. Slot 1; 112. Slot 2; 2. Mounting box; 21. Fixing plate; 22. Slot plate; 3. Positioning plate 1; 301. Contact sensor; 31. Support plate; 4. Positioning plate 2; 41. Lifting plate; 5. Rotating shaft; 51. Transmission gear; 511. Gear plate; 52. Servo motor; 53. Support rod; 54. Guide pin; 6. Hollow plate; 601. Support column; 61. Variable frequency fan; 62. Air blowing hole; 7. Photoelectric sensor. Detailed Implementation

[0039] The technical solution of the present invention will now be clearly and completely described with reference to specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0040] Reference Figure 1-7 A paper positioning device for a sheet-fed printing press, comprising:

[0041] The support frame 1 and the positioning platform 11 are fixed on the support frame 1. The positioning platform 11 has two parallel strip openings 111 and two strip openings 112. A support plate 31 is slidably installed in each of the two strip openings 112. A positioning plate 4 is slidably installed in the strip opening 111.

[0042] Two positioning plates 3 are fixedly installed on the top side of the corresponding support plate 31;

[0043] Mounting box 2 is located on the bottom side of support frame 1;

[0044] Two toothed plates 511 are slidably mounted on the mounting box 2. The two toothed plates 511 are fixedly connected to the corresponding support plates 31. A servo motor 52 is fixedly mounted on one side of the mounting box 2. A rotating shaft 5 is connected to the output shaft of the servo motor 52. A transmission gear 51 that meshes with the two toothed plates 511 is fixedly sleeved on the rotating shaft 5. The distance between the two positioning plates 3 can be quickly and accurately adjusted as needed, so as to limit the paper from the front and rear sides of the paper feeding direction. With the cooperation of multiple contact sensors 301, the paper positioning effect on the front and rear sides can be achieved.

[0045] A lifting plate 41 is fixedly installed on the bottom side of the positioning plate 2, which slides in contact with the inner walls of the front and rear sides of the mounting box 2. A guide groove is provided on the lifting plate 41. A support rod 53 is radially fixedly installed on the end of the rotating shaft 5. A guide pin 54 is radially fixedly installed on the support rod 53. The guide pin 54 is slidably installed in the guide groove. When the rotating shaft 5 rotates, it can control the lifting plate 41 to drive the positioning plate 2 4 to adjust the height synchronously. This enables the linkage between the positioning plate 2 4 and the two positioning plates 3, thereby effectively simplifying the operation process, reducing the setting of independent drive components, and improving the synchronization and stability of the device operation.

[0046] Multiple contact sensors 301 are fixedly installed on the sides of two positioning plates 3 that are close to each other. Multiple contact sensors 301 on the same positioning plate 3 must be triggered simultaneously to determine that the paper has completed its forward and backward positioning. This avoids positioning deviations caused by accidental activation of a single contact sensor 301 and improves the accuracy of positioning judgment. Each of the two positioning plates 3 has a fixed elastic buffer pad with a thickness of 3-5mm, such as an elastic buffer pad made of polyurethane material. Multiple contact sensors 301 are embedded in the corresponding elastic buffer pads on their respective sides. This provides good cushioning when the paper contacts the positioning plate 3, preventing creases or damage to the paper due to rigid impact, and also preventing obstruction of the contact sensors 301. No specific model of the contact sensors 301 is specified; those skilled in the art can directly purchase and install them from the market according to the actual situation.

[0047] Four support columns 601 are fixedly installed on the support frame 1. A hollow plate 6 is fixedly installed on the top of the four support columns 601 for stable support of the hollow plate 6. A variable frequency fan 61 is fixedly installed on the top side of the hollow plate 6. The air outlet of the variable frequency fan 61 is connected to the hollow plate 6. Multiple air holes 62 are arranged in a circular array on the bottom inner wall of the hollow plate 6, with the midpoint of the top side of the positioning platform 11 as the center. The paper can be blown and positioned by blowing air onto the positioning platform 11 through the multiple air holes 62, while avoiding wrinkles. The air pressure blown into the hollow plate 6 by the machine 61 is a low-pressure air source, with the pressure range controlled within 0.02-0.05MPa. The pressure is adjusted according to the weight of a single sheet of paper to prevent the paper from detaching from the positioning plate 11 due to excessive air force. If the weight of a single sheet of paper is low (e.g., 60-80g / ㎡), the air pressure can be adjusted to 0.02-0.03MPa. If the weight of a single sheet of paper is high (e.g., 150-200g / ㎡), the air pressure can be adjusted to 0.04-0.05MPa to ensure that the paper can be effectively flattened without causing excessive impact to the paper.

[0048] The photoelectric sensor 7 is fixedly installed on the bottom side of the hollow plate 6, with its sensing probe facing the center area of ​​the top side of the positioning platform 11. When the paper is fed onto the positioning platform 11, the photoelectric sensor 7 can quickly detect the presence of the paper within 0.1 seconds and immediately trigger the variable frequency fan 61 and servo motor 52 to start, realizing the automatic start of the positioning process. If no paper is detected within a set time (such as 2 seconds), the system automatically enters the standby state to reduce energy consumption.

[0049] The angles between the axes of the multiple air holes 62 and the axis containing the midpoint of the top side of the positioning platform 11 increase progressively from the inside out. The tilt angles of the air holes 62, excluding the central air hole 62, are within the range of 15-30 degrees. For example, the angles of the innermost 3-4 air holes 62 are set at 5-10 degrees, the angles of the middle layer 6-8 air holes 62 are set at 15-20 degrees, and the angles of the outermost 8-10 air holes 62 are set at 25-30 degrees. This gradient angle design allows the airflow to radially diffuse from the center outwards, with the wind force gradually increasing outwards. This enables more precise application to different areas of the paper and avoids potential issues when the angle is less than 15 degrees. The current radial force is insufficient, resulting in poor stretching effect. At the same time, it avoids the airflow dispersion that may occur when the angle is greater than 30°. For the middle of the paper near the center, a smaller angle and wind force can prevent the center of the paper from bulging excessively. For the edges of the paper that are prone to warping, a larger angle and wind force can more effectively smooth and unfold them. The airflow that diffuses from the center to the surrounding area can effectively counteract the warping and internal stress of the paper itself, making the paper more evenly stressed during the positioning process and fully unfolding its edges. This eliminates warping and wrinkles caused by storage and transportation, and ensures that the paper is flat before positioning by positioning plate 3 and positioning plate 4, further improving the positioning accuracy.

[0050] To guide the airflow when it blows from the air outlet 62 onto the paper on the positioning plate 11 and causes it to swirl downwards at the paper's edge, thus preventing the paper from being blown off the positioning plate 11, a through hole is provided at the midpoint of the top side of the positioning plate 11. Multiple radially arranged air guide grooves are formed on the top side of the positioning plate 11 around the through hole. The diameter of the through hole is 8-10 mm, and 8-12 radially arranged air guide grooves are formed on the top side of the positioning plate 11 around the through hole. The width of the air guide grooves is 2-3 mm, and the depth is 1-1.5 mm. m, and the length of the air guide groove extends from the central through hole to near the edge of the positioning plate 11. When the airflow blown out by the air blowing hole 62 acts on the paper surface and spreads to the edge, some airflow will flow downwards at the edge of the paper. At this time, the air guide groove can guide this part of the flowing air to the bottom of the positioning plate 11 in time, avoiding the airflow from accumulating at the bottom of the paper to form an air cushion and blowing the paper up, ensuring that the paper always adheres to the surface of the positioning plate 11, providing a stable foundation for subsequent mechanical positioning. In addition, low-pressure air flotation is used in the positioning stage, and the air pressure is reduced after positioning is completed, so that the paper adheres smoothly to the positioning plate 11.

[0051] In this embodiment, to provide effective support for the rotating shaft 5 and the mounting box 2, and to facilitate disassembly, a fixing plate 21 is fixedly installed inside the mounting box 2. The fixing plate 21 has an installation opening, and a bearing is fixedly installed inside the installation opening. The inner ring of the bearing is fixedly fitted onto the outside of the rotating shaft 5. Strip plates 22 are fixedly installed on the top of both sides of the mounting box 2. Each strip plate 22 is fixed to the bottom of the support frame 1 by at least two bolts. The strip plates 22 and the mounting box 2 are integrally formed. Each strip plate 22 has two... The waist-shaped mounting hole has a length that can be set as needed, such as 20-30mm, to facilitate fine-tuning of its position during installation. The strip plate 22 is fixed to the crossbeam on the bottom side of the support frame 1 with hexagonal bolts. Anti-loosening washers are provided at the bolt connections to ensure that the mounting box 2 will not loosen due to vibration during equipment operation. This detachable connection method allows the mounting box 2 to be completely removed simply by unscrewing the bolts when components such as the servo motor 52 and transmission gear 51 inside the mounting box 2 need maintenance or replacement. This greatly simplifies the maintenance operation process and reduces downtime for maintenance.

[0052] In this embodiment, in order to effectively reduce the weight of the lifting plate 41 and the second positioning plate 4, thereby reducing the energy consumption during the lifting of the positioning plate and improving the operating efficiency of the device, cavities are provided on the side of the second positioning plate 4 and the lifting plate 41 away from the first positioning plate 3. The depth of the cavity is 1 / 3 to 1 / 2 of the thickness of the second positioning plate 4 and the lifting plate 41, and the inner wall of the cavity is smoothed to avoid stress concentration while reducing the weight. Taking the second positioning plate 4 as an example, it is made of high-strength aluminum alloy. After the cavity is opened, the weight is reduced by about 35% compared with the solid structure, which reduces the inertia when the lifting plate 41 drives the second positioning plate 4 to lift and lower, and reduces the load on the servo motor 52. This not only reduces energy consumption, but also improves the response speed and control accuracy of the height adjustment of the second positioning plate 4.

[0053] The control of the servo motor 52, contact sensor 301 and photoelectric sensor 7 are all set according to existing known technologies and integrated into the control system of the sheet printing machine to achieve centralized control.

[0054] Working principle: When in use, first turn on the power and transport the sheet of paper to be printed to the top center area of ​​the positioning plate 11. At this time, the photoelectric sensor 7 will quickly detect the presence of the paper and immediately send a signal to the control system of the sheet printing machine, triggering the variable frequency fan 61 and servo motor 52 to start. After the variable frequency fan 61 starts, it sends a low-pressure air source into the hollow plate 6. The air is blown out through multiple air holes 62 opened on the bottom inner wall of the hollow plate 6, forming an airflow that diffuses from the center to the surroundings with increasing wind force. This airflow acts on the paper surface and can effectively counteract the warping and internal stress of the paper, smoothing and unfolding the edges of the paper that are prone to warping. At the same time, the air guide groove on the top side of the positioning plate 11 guides the airflow downward around the edge of the paper to the bottom of the positioning plate 11 in time, avoiding the formation of an air cushion at the bottom of the paper and blowing it up, ensuring that the paper is flat and adhered to the surface of the positioning plate 11.

[0055] While the variable frequency fan 61 is working, the servo motor 52 starts, and its output shaft drives the rotating shaft 5 to rotate. The rotating shaft 5 drives the guide pin 54 to slide in the guide groove through the support rod 53, thereby driving the lifting plate 41 to slide up and down along the inner walls of the front and rear sides of the mounting box 2. This allows the positioning plate 2 4 to be adjusted in height synchronously with the lifting plate 41, thus enabling auxiliary positioning or limiting from the paper conveying direction. At the same time, its rotating shaft 5 drives the transmission gear 51 to rotate, causing the two toothed plates 511 to drive the corresponding support plate 31 and positioning plate 3 to slide in opposite directions, thereby precisely adjusting the distance between the two positioning plates 3 to adapt to the current paper size. This achieves the linkage control between positioning plate 3 and positioning plate 4. When the positioning plate 3 moves and comes into contact with the multiple contact sensors 301 embedded in the elastic buffer pad, the servo motor 52 stops rotating, achieving precise limiting of the paper in the front and rear directions. The elastic buffer pad can prevent the paper from creases or damage due to rigid collision.

[0056] If the photoelectric sensor 7 does not detect paper within the set 2-second time, the system automatically enters standby mode to reduce energy consumption. The whole process is highly automated, with significantly improved positioning accuracy and efficiency, and it has good adaptability to paper of different specifications and thicknesses.

[0057] The foregoing has provided a detailed description of a paper positioning device for a sheet-fed printing press. Specific embodiments have been used to illustrate the principles and implementation methods of the invention. These embodiments are merely illustrative and are intended to aid in understanding the method and core concepts of the invention. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims.

Claims

1. A paper positioning device for a sheet-fed printing press, characterized in that, include: Support frame (1); The positioning platform (11) is fixed on the support frame (1), and the positioning platform (11) has a parallel strip opening 1 (111) and two strip openings 2 (112). A support plate (31) is slidably installed in each of the two strip openings 2 (112), and a positioning plate 2 (4) is slidably installed in the strip opening 1 (111). Two positioning plates (3) are fixedly installed on the top side of the corresponding support plate (31); Mounting box (2) is located on the bottom side of support frame (1); The spacing adjustment component is mounted on the mounting box (2) and connected to the two support plates (31); The linkage component is mounted on the spacing adjustment component and connected to the positioning plate two (4); Multiple contact sensors (301) are fixedly installed on the side of the two positioning plates (3) that are close to each other; The blowing component is located above the support frame (1). The blowing component can blow and position the paper on the positioning platform (11). A photoelectric sensor (7) is installed on the blowing assembly to detect whether there is paper on the positioning platform (11).

2. The paper positioning device for a sheet-fed printing press according to claim 1, characterized in that: The spacing adjustment assembly includes a servo motor (52), a transmission gear (51), and two toothed plates (511). Two toothed plates (511) are slidably mounted on the mounting box (2). The two toothed plates (511) are fixedly connected to the corresponding support plates (31). A servo motor (52) is fixedly mounted on one side of the mounting box (2). A rotating shaft (5) is connected to the output shaft of the servo motor (52). A transmission gear (51) that meshes with the two toothed plates (511) is fixedly sleeved on the rotating shaft (5).

3. The paper positioning device for a sheet-fed printing press according to claim 1, characterized in that: The linkage assembly includes a support rod (53), a guide pin (54), and a lifting plate (41). The bottom side of the positioning plate (4) is fixedly installed with a lifting plate (41) that slides in contact with the inner walls of the front and rear sides of the mounting box (2). A guide groove is provided on the lifting plate (41). The end of the rotating shaft (5) is radially fixedly installed with a support rod (53). A guide pin (54) is radially fixedly installed on the support rod (53). The guide pin (54) is slidably installed in the guide groove.

4. The paper positioning device for a sheet-fed printing press according to claim 1, characterized in that: The blowing assembly includes a hollow plate (6), a variable frequency fan (61), and multiple air holes (62). Four support columns (601) are fixedly installed on the support frame (1). The hollow plate (6) is fixedly installed on the top of the four support columns (601). The variable frequency fan (61) is fixedly installed on the top side of the hollow plate (6). The air outlet of the variable frequency fan (61) is connected to the hollow plate (6). Multiple air holes (62) are arranged in a circular array with the midpoint of the top side of the positioning platform (11) as the center on the bottom inner wall of the hollow plate (6). The photoelectric sensor (7) is fixedly installed on the bottom side of the hollow plate (6).

5. The paper positioning device for a sheet-fed printing press according to claim 4, characterized in that: The angle between the axis of the multiple air holes (62) and the axis of the midpoint of the top side of the positioning plate (11) increases from the inside to the outside, and the tilt angle of the multiple air holes (62) except for the air hole (62) at the center position is within the range of 15-30 degrees.

6. The paper positioning device for a sheet-fed printing press according to claim 1, characterized in that: The positioning platform (11) has a through hole at the midpoint of its top side, and multiple radially arranged air guide grooves are formed on the top side of the positioning platform (11) with the through hole as the center.

7. The paper positioning device for a sheet-fed printing press according to claim 3, characterized in that: A fixing plate (21) is fixedly installed inside the mounting box (2). An installation port is provided on the fixing plate (21). A bearing is fixedly installed inside the installation port, and the inner ring of the bearing is fixedly sleeved on the outside of the rotating shaft (5).

8. The paper positioning device for a sheet-fed printing press according to claim 3, characterized in that: Both the second positioning plate (4) and the lifting plate (41) have cavities on the side away from the first positioning plate (3).

9. The paper positioning device for a sheet-fed printing press according to claim 1, characterized in that: Two positioning plates (3) are fixedly installed with elastic buffer pads on the side that are close to each other. The thickness of the elastic buffer pads is 3-5mm, and multiple contact sensors (301) are embedded and fixed in the elastic buffer pads on the corresponding side.

10. A paper positioning device for a sheet-fed printing press according to claim 1, characterized in that: The top of both sides of the mounting box (2) is fixedly installed with strip plates (22), and both strip plates (22) are fixed to the bottom side of the support frame (1) by at least two bolts.

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