A die cutting mechanism for a water mark printing press

Abstract

The present application relates to the field of printing equipment, specifically is a kind of die-cutting mechanism for watermark printing machine, including rotation setting on the printing machine die roller and rubber roller, die roller is located in the upper part of rubber roller, die roller is provided with the die mechanism for pressing out indentation on corrugated board, the present application adopts rotating die roller to drive indentation cutter to contact with corrugated board periodically, and the vertical impact force when indentation cutter and corrugated board initial contact is buffered through buffer assembly, instantaneous concentrated rigid impact is converted into flexible progressive contact, effectively avoid the phenomenon of corrugated core plastic deformation and crush due to excessive impact load;At the same time, during the indentation cutter contact paperboard, use kneading component to pressurized area corrugated board to exert horizontal direction reciprocating kneading action, so that fiber obtains adaptive stretch in indentation process, significantly reduce the risk of fiber tensile stress exceeding limit, ensure subsequent folding forming precision and carton product structure strength.

Description

Technical Field

[0001] This invention relates to the field of printing equipment, specifically a die-cutting mechanism for a watermark printing machine. Background Technology

[0002] As the most widely used packaging product, corrugated cardboard boxes require a die-cutting process after watermark printing. The die-cutting process generally includes two core actions: first, removing excess material from the corrugated cardboard, and second, pressing creases into the cardboard for subsequent folding. The quality of the crease process directly determines the folding accuracy and finished strength of the cardboard box.

[0003] Rotary die-cutting is currently the most widely used die-cutting method in corrugated box printing lines. Its working principle is as follows: between the high-speed rotating die-cutting roller and the pad roller, the creasing knife installed on the surface of the die-cutting roller makes pressure contact with the cardboard, so that the creasing knife applies radial pressure to the cardboard, causing the corrugated cardboard to be deformed under pressure, thereby pressing out the required fold lines on the cardboard.

[0004] However, in existing rotary die-cutting mechanisms, the creasing knife is usually fixedly mounted on the circumferential surface of the creasing knife roller. When the roller rotates, the creasing knife rotates with the roller, pressing into the paperboard with a fixed radial height and a single direction of movement for a very short time in contact with the paperboard. This traditional fixed creasing structure exposes the following technical problems in actual production: First, the moment the creasing knife contacts the cardboard, all the creasing force is concentrated on the corrugated cardboard in a "vertical impact" manner. This causes the corrugated cardboard to bear instantaneous concentrated pressure in a very short time, resulting in irreversible plastic deformation of the corrugated core layer, that is, the corrugation is "crushed". This phenomenon significantly reduces the edge crush strength of the cardboard at the creasing line, thereby weakening the overall compression resistance and stacking performance of the finished carton.

[0005] Secondly, during the creasing process, when the fixed creasing knife impacts and pushes the corrugated cardboard instantly, it can cause the fibers in the pressure area of ​​the cardboard to be stretched rapidly. When the tensile stress exceeds the tensile limit of the fibers themselves, it is very easy for visible or potential micro-tears to occur at the edge of the creasing line. This tearing not only affects the appearance of the carton, but also becomes a stress concentration point during subsequent folding and use, causing the carton to break and fail along the creasing line. Summary of the Invention

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a die-cutting mechanism for a watermark printing machine, including a pressing roller and a rubber roller rotatably mounted on the printing machine, the pressing roller being located above the rubber roller, and the pressing roller being provided with a pressing mechanism for pressing indentations on corrugated cardboard.

[0007] The molding mechanism includes a creasing knife connected inside the molding roller via a buffer assembly. The creasing knife consists of two symmetrical parts. The molding mechanism also includes a kneading assembly disposed on the buffer assembly. The kneading assembly is used to reciprocate the two parts of the creasing knife in opposite directions, thereby dispersing the stress of the corrugated cardboard through the creasing knife.

[0008] The molding mechanism also includes an ejection component disposed in the molding roller. When the molding roller rotates, it drives the creasing knife to periodically contact the corrugated cardboard. When in contact, the buffer component buffers the impact of the creasing knife on the corrugated cardboard, while the kneading component kneads the corrugated cardboard. Then the ejection component gradually ejects the creasing knife, so that the creasing knife makes a creasing on the corrugated cardboard.

[0009] In summary, by using the impact of cushioning on the corrugated cardboard, kneading the corrugated cardboard, and gradually ejecting the creasing knife, the creasing process is completed when the creasing knife contacts the corrugated cardboard.

[0010] Preferably, the buffer assembly includes a base plate fixedly connected to the inside of the molding roller, and a movable plate slidably connected to the side of the base plate away from the axis of the molding roller.

[0011] Preferably, a guide post is fixedly connected to the side of the movable plate near the axis of the molding roller, the guide post is slidably connected to the base plate, and a buffer spring is provided between the movable plate and the base plate.

[0012] Preferably, two receiving plates are slidably connected to the side of the movable plate away from the axis of the pressing roller, and the two receiving plates move in opposite directions along the axial direction of the pressing roller.

[0013] Preferably, the receiving plate and the embossing knife at the corresponding position are fixedly connected together by screws in a quick-detachable manner, so that the two parts of the embossing knife are combined together to press the indentation.

[0014] Preferably, the kneading assembly includes a connecting column fixedly installed on the side of the receiving plate near the axis of the pressing roller, and a swing groove plate rotatably provided on the side of the moving plate near the axis of the pressing roller. The swing groove plate and the two connecting columns are slidably connected through a groove.

[0015] Preferably, an actuator motor is fixedly installed on the side of the moving plate near the axis of the pressure roller, and the actuator motor drives the swing groove plate to swing back and forth through a crank rocker structure.

[0016] Preferably, the ejection assembly includes a cam rod rotatably connected to a coaxial position inside the die roller, and the cam rod is fixedly connected to the printing press frame.

[0017] Preferably, the ejection assembly further includes a connecting roller rotatably connected to the side of the moving plate near the axis of the pressing roller. When the pressing roller rotates, the pressing roller drives the connecting roller to move along the trajectory of the cam rod.

[0018] Preferably, the side of the indentation knife away from the axis of the die roller has a wavy structure, and the wavy structure of the indentation knife has rounded corners.

[0019] The beneficial effects of this invention are as follows: First, this invention uses a rotating pressing roller to drive the creasing knife to periodically contact the corrugated cardboard, and uses a buffer component to buffer the vertical impact force when the creasing knife initially contacts the corrugated cardboard, transforming the instantaneously concentrated rigid impact into a flexible, progressive contact. This effectively avoids plastic deformation and crushing of the corrugated core layer caused by excessive impact load, thereby maintaining the integrity of the edge crush strength at the creasing line. At the same time, during the contact between the creasing knife and the cardboard, a kneading component applies a horizontal reciprocating kneading motion to the corrugated cardboard in the pressure area. On the one hand, this dynamically disperses the radial impact stress concentration, and on the other hand, the kneading action soothes the rapid stretching of the cardboard fibers, allowing the fibers to adapt and stretch during the creasing process. This significantly reduces the risk of fiber tensile stress exceeding the limit, thereby effectively preventing micro-tears or macro-cracks at the edge of the creasing line, ensuring the accuracy of subsequent folding and forming and the structural strength of the finished carton.

[0020] Second, in this invention, when the creasing knife touches the surface of the corrugated cardboard, the buffer spring first absorbs the initial contact kinetic energy and generates elastic compression. The moving plate generates relative displacement along the guide post, thereby effectively buffering and attenuating the impact peak at the moment of contact. As the pressing roller continues to rotate, the moving plate drives the connecting roller to move along the circumferential contour trajectory of the cam rod and enter its push-stroke curve stage. This allows the creasing knife to gradually press into the corrugated cardboard in a progressively increasing manner after the buffering stage, thereby creating a creasing line with uniform depth and controllable deformation on the cardboard. This eliminates the risk of crushing and tearing caused by the creasing knife piercing the cardboard at full height instantaneously in the traditional structure.

[0021] Third, this invention employs an actuator motor that drives a swinging slot plate to reciprocate back and forth at high frequency around its axis via a crank-rocker structure. This causes the receiving plate to drive the two parts of the crease knife to produce periodic reverse kneading displacement. This allows the fibers in the pressure area of ​​the cardboard to be repeatedly pushed and stretched horizontally while being subjected to radial pressure. This effectively disperses the local stress concentration caused by the crease knife pressing in, promotes the uniform distribution and dissipation of stress in a larger fiber area, effectively curbs the occurrence of fiber tensile breakage, and significantly improves the tear resistance of the crease line edge.

[0022] Fourth, this invention uses a creasing knife with a wavy profile to knead the corrugated cardboard. The alternating peaks and troughs of the creasing knife create a continuous stirring and massaging effect on the cardboard fibers, further enhancing the soothing effect of the kneading action on the stretched state of the cardboard fibers and preventing micro-cracks caused by excessive local stretching. At the same time, a rounded corner structure is provided at the edge of the wavy blade of the creasing knife to prevent the creasing knife from cutting the cardboard during kneading and pressing, thus taking into account both the quality of the creasing line formation and the integrity of the cardboard substrate. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the structure of the pressure roller, the indentation knife, and the ejection assembly in this invention; Figure 3 This is a partial cross-sectional view of the pressure roller, indentation knife, and cam rod in this invention; Figure 4 This is a partial cross-sectional view of the pressure roller, buffer assembly, indentation knife, and ejection assembly in this invention; Figure 5 This is a schematic diagram of the structure of the moving plate, cam rod, indentation knife and receiving plate in this invention; Figure 6 This is a partial sectional view of the indentation tool, connecting column, and bearing plate in this invention; Figure 7 This is a schematic diagram of the structure of the movable plate, the base plate, the receiving plate and the connecting roller in this invention; Figure 8 This is a partial sectional view of the receiving plate, the moving plate, the connecting column, and the swing groove plate in this invention; Figure 9 This is a partial cross-sectional view of the swing slot plate and the actuator motor in this invention; Figure 10 This is a partial cross-sectional view of the movable plate, guide column, connecting roller and cam rod in this invention.

[0025] In the diagram: 1. Pressing roller; 2. Rubber roller; 3. Pressing mechanism; 31. Buffer assembly; 32. Indentation knife; 33. Kneading assembly; 34. Ejection assembly; 311. Base plate; 312. Moving plate; 313. Guide column; 314. Receiving plate; 331. Connecting column; 332. Swinging groove plate; 333. Actuating motor; 341. Cam rod; 342. Connecting roller. Detailed Implementation

[0026] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or in accordance with the product manual.

[0027] See Figure 1 , Figure 2 and Figure 3 A die-cutting mechanism for a watermark printing machine includes a die-cutting roller 1 and a rubber roller 2 rotatably mounted on the printing machine. The die-cutting roller 1 is located above the rubber roller 2, and a die-cutting mechanism 3 for pressing indentations on corrugated cardboard is provided on the die-cutting roller 1.

[0028] When printing corrugated cardboard, the operator places the stacked corrugated cardboard at the feeding port of the watermark printing machine, starts the printing machine to feed the corrugated cardboard one by one into the printing machine for printing. After printing, the printing machine automatically conveys the corrugated cardboard to the die-cutting mechanism of the printing machine, so that the die-cutting mechanism 3 makes creases on the corrugated cardboard, cuts off excess material, and presses creases on the cardboard for subsequent folding and forming.

[0029] In this embodiment, two synchronous motors are fixedly installed on the outside of the printing machine frame. One synchronous motor has a drive pulley fixedly installed on its output shaft, and a driven pulley is fixedly installed on the outside of the shaft of the pressure roller 1. A belt is wound between the drive pulley and the driven pulley. The output shaft of the other synchronous motor is fixedly connected to the rubber roller 2. During printing, the two synchronous motors are started to drive the pressure roller 1 and the rubber roller 2 to rotate synchronously in opposite directions, so that the pressure roller 1 and the rubber roller 2 drive the corrugated cardboard to move continuously when they rotate.

[0030] See Figure 1 , Figure 4 , Figure 5 and Figure 6 The molding mechanism 3 includes a creasing knife 32 connected inside the molding roller 1 via a buffer assembly 31. The creasing knife 32 consists of two symmetrical parts. The molding mechanism 3 also includes a kneading assembly 33 disposed on the buffer assembly 31. The kneading assembly 33 is used to reciprocate the two parts of the creasing knife 32 in opposite directions, thereby dispersing the stress of the corrugated cardboard through the creasing knife 32.

[0031] Continue reading Figure 1 , Figure 4 , Figure 5 and Figure 6The molding mechanism 3 also includes an ejection component 34 disposed in the molding roller 1. When printing corrugated cardboard, the molding roller 1 is continuously rotated, so that the molding roller 1 drives the creasing knife 32 to periodically contact the corrugated cardboard through the buffer component 31. When the creasing knife 32 initially contacts the corrugated cardboard, the buffer component 31 buffers the impact of the creasing knife 32 on the corrugated cardboard, thereby transforming the instantaneously concentrated rigid impact into a flexible and progressive contact, effectively avoiding plastic deformation and crushing of the corrugated core layer caused by excessive impact load, thereby maintaining the integrity of the edge pressure strength at the creasing line.

[0032] During printing, the two parts of the creasing knife 32 are moved back and forth by the kneading component 33, so that the fibers in the pressure area of ​​the corrugated cardboard are repeatedly pushed and stretched in the horizontal direction while being subjected to radial pressure. This effectively disperses the local stress concentration caused by the creasing knife 32 pressing in, promotes the uniform distribution and dissipation of stress in a larger fiber area, effectively curbs the occurrence of fiber tensile breakage, and significantly improves the tear resistance of the creasing line edge.

[0033] Subsequently, as the pressing roller 1 rotates, the creasing knife 32 is pushed out gradually by the ejection component 34 after the buffering stage, so that the creasing knife 32 gradually presses into the corrugated cardboard, thereby creating a creasing line with uniform depth and controllable deformation on the cardboard, eliminating the crushing and tearing risks caused by the creasing knife 32 instantly piercing the cardboard at full height in the traditional structure.

[0034] To more conveniently cushion the impact of the creasing knife 32 on the corrugated cardboard, the present invention designs the following structure: (See attached diagram) Figure 4 , Figure 5 and Figure 7 The buffer assembly 31 includes a base plate 311 fixedly connected to the inner side of the molding roller 1. A movable plate 312 is slidably connected to the side of the base plate 311 away from the axis of the molding roller 1. A guide post 313 is fixedly connected to the side of the movable plate 312 close to the axis of the molding roller 1. The guide post 313 is slidably connected to the base plate 311. A buffer spring is provided between the movable plate 312 and the base plate 311.

[0035] See Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 and Figure 9 Two receiving plates 314 are slidably connected to the side of the moving plate 312 away from the axis of the pressing roller 1. The two receiving plates 314 move in opposite directions along the axis of the pressing roller 1. The receiving plates 314 and the corresponding indentation knife 32 are fixedly connected together by screws in a quick-disassembly manner, so that the two parts of the indentation knife 32 are combined together to press the indentation.

[0036] When the pressing roller 1 rotates, the pressing roller 1 drives the moving plate 312 to rotate synchronously through the base plate 311. The moving plate 312 drives the two parts of the creasing knife 32 to rotate synchronously through the two receiving plates 314. When the creasing knife 32 touches the surface of the corrugated cardboard, the buffer spring absorbs the initial contact kinetic energy first and generates elastic compression. The moving plate 312 generates relative displacement along the guide post 313, thereby effectively buffering and attenuating the impact peak at the moment of contact and preventing rigid impact from crushing the corrugated cardboard.

[0037] To prevent the corrugated cardboard fibers from tearing due to pressure and sinking when the creasing knife 32 presses the corrugated cardboard, the present invention is designed with the following structure: (See attached diagram) Figure 5 , Figure 6 , Figure 7 , Figure 8 and Figure 9 The kneading assembly 33 includes a connecting column 331 fixedly installed on the receiving plate 314 near the axis of the pressing roller 1, and a swing groove plate 332 rotatably provided on the moving plate 312 near the axis of the pressing roller 1. The swing groove plate 332 and the two connecting columns 331 are slidably connected through the groove.

[0038] See Figure 6 , Figure 7 , Figure 8 and Figure 9 An actuator motor 333 is fixedly installed on the side of the movable plate 312 near the axis of the pressure roller 1. The actuator motor 333 drives the swing groove plate 332 to swing back and forth through a crank rocker structure.

[0039] When the pressing roller 1 rotates, the start-up motor 333 drives the swing groove plate 332 to swing back and forth through the crank rocker structure. This causes the swing groove plate 332 to swing back and forth at high frequency around its axis. The groove on the swing groove plate 332 and the connecting post 331 at the bottom of the receiving plates 314 on both sides form a sliding fit relationship. This converts the reciprocating rotation of the swing groove plate 332 into the linear reciprocating movement of the two receiving plates 314 in opposite directions along the axis of the pressing roller 1. This causes the receiving plates 314 to drive the two parts of the creasing knife 32 to produce periodic reverse kneading displacement. This allows the fibers in the pressure area of ​​the cardboard to be repeatedly pushed and stretched in the horizontal direction while being subjected to radial pressure. This effectively disperses the local stress concentration caused by the creasing knife 32 pressing in, promotes the uniform distribution and dissipation of stress in a larger fiber area, effectively inhibits the occurrence of fiber tensile breakage, and significantly improves the tear resistance of the creasing line edge.

[0040] The crank-rocker structure in this embodiment includes a crank disc fixedly mounted on the output shaft of the actuator motor 333, a rocker arm hinged to the edge of the crank disc, and the other end of the rocker arm hinged to the swing groove plate 332, with the hinge point between the rocker arm and the swing groove plate 332 being away from the axis of rotation of the swing groove plate 332.

[0041] In order for the creasing knife 32 to make creasing marks on corrugated cardboard, the present invention is designed with the following structure: (See reference) Figure 4 , Figure 5 and Figure 10 The ejection assembly 34 includes a cam rod 341 rotatably connected to the inside of the die roller 1 at a coaxial position. The cam rod 341 is fixedly connected to the printing machine frame. The ejection assembly 34 also includes a connecting roller 342 rotatably connected to the side of the moving plate 312 near the axis of the die roller 1. When the die roller 1 rotates, the die roller 1 drives the connecting roller 342 to move along the trajectory of the cam rod 341.

[0042] When the pressing roller 1 rotates, it synchronously drives the moving plate 312 to rotate, so that the moving plate 312 drives the connecting roller 342 to move along the circumferential contour trajectory of the cam rod 341. When the connecting roller 342 moves into the push curve stage of the cam rod 341, the creasing knife 32 ends the buffer stage, so that the cam rod 341 pushes the connecting roller 342 to move the moving plate 312 radially, so that the moving plate 312 drives the creasing knife 32 to gradually press into the corrugated cardboard in a progressively increasing manner, thereby creating a creasing line with uniform depth and controllable deformation on the cardboard, eliminating the crushing and tearing hazards caused by the creasing knife 32 instantly piercing the cardboard at full height in the traditional structure.

[0043] To improve the creasing effect of the creasing knife 32 on corrugated cardboard, the present invention designs the following structure: (See reference) Figure 2 , Figure 5 and Figure 6 The side of the indentation knife 32 away from the axis of the die roller 1 has a wavy structure, and the wavy structure of the indentation knife 32 has rounded corners.

[0044] When the wavy contour structure of the creasing knife 32 kneads the corrugated cardboard, the alternating peaks and troughs of the wavy shape continuously agitate and massage the cardboard fibers, further enhancing the soothing effect of the kneading action on the stretched state of the cardboard fibers and preventing micro-cracks caused by excessive local stretching. At the same time, the rounded corner structure at the edge of the wavy blade of the creasing knife 32 prevents the creasing knife 32 from cutting the cardboard during the kneading and pressing process, thus taking into account both the quality of the creasing line formation and the integrity of the cardboard substrate.

[0045] Although this invention adds a crumpling component 33, a buffer component 31, and an ejection component 34 to the traditional die-cutting mechanism, increasing the number of equipment parts and slightly increasing the initial manufacturing cost and assembly complexity, it effectively suppresses the rigid impact load when the creasing knife 32 initially contacts the corrugated cardboard through an elastic buffering mechanism. This fundamentally avoids plastic deformation and crushing defects in the corrugated core layer due to impact overload, thus ensuring the integrity of the edge crush strength at the creasing line and significantly reducing the scrap rate and material loss caused by cardboard crushing. At the same time, the two parts of the crumpling component 33 driving the creasing knife 32 apply horizontal reciprocating pushing and stretching to the cardboard fibers during the creasing process, allowing the cardboard fibers to obtain sufficient stress dispersion and stretching relief while being radially compressed. This effectively curbs the generation of micro-tears or macro-cracks at the edge of the creasing line, ensuring the accuracy and stability of subsequent folding and forming processes and the structural strength of the finished carton.

[0046] The process optimization achieved through the synergistic effect of the above structures can quickly balance or even offset the increase in initial investment from multiple dimensions. Specifically, the improvement in process quality directly reduces the hidden operating costs caused by returns and rework due to indentation quality defects and production interruptions, thereby quickly realizing the recovery of initial investment costs and positive gains in overall economic benefits in actual production applications.

[0047] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0048] Furthermore, the terms "first," "second," "number one," and "number two" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," "number one," or "number two" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0049] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0050] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A die-cutting mechanism for a watermark printing machine, comprising a pressure roller and a rubber roller rotatably mounted on the printing machine, the pressure roller being located above the rubber roller, characterized in that, The pressing roller is equipped with a pressing mechanism for pressing indentations into the corrugated cardboard; The molding mechanism includes a creasing knife connected inside the molding roller via a buffer assembly. The creasing knife consists of two symmetrical parts. The molding mechanism also includes a kneading assembly disposed on the buffer assembly. The kneading assembly is used to reciprocate and move the two parts of the creasing knife in opposite directions, thereby dispersing the stress of the corrugated cardboard through the creasing knife. The molding mechanism also includes an ejection component disposed in the molding roller. When the molding roller rotates, it drives the creasing knife to periodically contact the corrugated cardboard. When in contact, the buffer component buffers the impact of the creasing knife on the corrugated cardboard, while the kneading component kneads the corrugated cardboard. Then the ejection component gradually ejects the creasing knife, so that the creasing knife makes a creasing on the corrugated cardboard. By using a cushioning mechanism to absorb the impact of the corrugated cardboard, knead the cardboard, and gradually eject the creasing knife, the creasing process is completed when the knife contacts the cardboard.

2. The die-cutting mechanism for a watermark printing machine according to claim 1, characterized in that, The buffer assembly includes a base plate fixedly connected to the inside of the molding roller, and a movable plate slidably connected to the side of the base plate away from the axis of the molding roller.

3. A die-cutting mechanism for a watermark printing machine according to claim 2, characterized in that, A guide post is fixedly connected to the side of the movable plate near the axis of the pressure roller. The guide post is slidably connected to the base plate, and a buffer spring is provided between the movable plate and the base plate.

4. A die-cutting mechanism for a watermark printing machine according to claim 2, characterized in that, Two receiving plates are slidably connected to the side of the movable plate away from the axis of the pressure roller, and the two receiving plates move in opposite directions along the axial direction of the pressure roller.

5. A die-cutting mechanism for a watermark printing machine according to claim 4, characterized in that, The receiving plate and the embossing knife at the corresponding position are fixed together by screws in a quick-detachable manner, so that the two parts of the embossing knife are combined together to press the indentation.

6. A die-cutting mechanism for a watermark printing machine according to claim 4, characterized in that, The kneading assembly includes a connecting column fixedly installed on the receiving plate near the axis of the pressing roller, and a swing groove plate rotatably provided on the moving plate near the axis of the pressing roller. The swing groove plate and the two connecting columns are slidably connected through the groove.

7. A die-cutting mechanism for a watermark printing machine according to claim 6, characterized in that, An actuator motor is fixedly installed on the side of the moving plate near the axis of the pressure roller. The actuator motor drives the swing groove plate to swing back and forth through a crank rocker structure.

8. A die-cutting mechanism for a watermark printing machine according to claim 2, characterized in that, The ejection assembly includes a cam rod rotatably connected to a coaxial position inside the compression roller, and the cam rod is fixedly connected to the printing press frame.

9. A die-cutting mechanism for a watermark printing machine according to claim 8, characterized in that, The ejection assembly also includes a connecting roller rotatably connected to the side of the moving plate near the axis of the pressure roller. When the pressure roller rotates, the pressure roller drives the connecting roller to move along the trajectory of the cam rod.

10. A die-cutting mechanism for a watermark printing machine according to claim 1, characterized in that, The side of the indentation knife away from the axis of the die roller has a wavy structure, and the wavy structure of the indentation knife has rounded corners.

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