Offset press post-printing cooling device and cooling method

Abstract

The invention discloses an offset press post-printing cooling device and a cooling method, and belongs to the technical field of printing cooling equipment. The device comprises a cooling roller with a built-in spiral flow guide groove and a waterway system, the spiral flow guide groove accelerates flowing of cooling liquid through the spiral pump effect, and the heat exchange efficiency is improved; the waterway system realizes automatic control of cooling liquid circulation through an electric three-way ball valve and a check valve, residual cooling liquid in the roller can be quickly emptied during shutdown, and dew formation, paper breakage and equipment corrosion are prevented. According to the cooling method, target parameters of the cooling liquid are set, real-time monitoring and closed-loop control are combined, the flow and the temperature are dynamically adjusted, and the residual cooling liquid is emptied through inertial rotation of the cooling roller. The high-speed printing cooling device solves the problems that an existing device is low in cooling efficiency, dews and breaks paper after shutdown, and equipment is rusted, and the cooling effect during high-speed printing is remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of printing cooling equipment, specifically relates to a post-print cooling device for an offset printing machine, and also relates to a post-print cooling method for an offset printing machine. Background Art

[0002] In the field of web printing, the post-print cooling device is a key equipment to ensure ink curing and print quality. In the prior art, the post-print cooling devices for offset printing machines are mainly divided into two categories: air-cooled type and water-cooled type: The traditional air-cooled cooling device drives a fan through an air-cooling mechanism at the top of the frame, and combines air intake filtering and cooling components such as a mesh plate, a semiconductor refrigerating sheet, and a honeycomb plate to make the air contact the printed matter on one side to achieve heat dissipation. Its working principle is to use forced convection to take away the heat on the surface of the printed matter. However, due to the low thermal conductivity of air, the single-sided cooling effect is poor. Especially when processing lightweight printed matter, it is easy to cause the paper to turn over, resulting in uneven cooling and affecting the print quality; the water-cooled cooling device uses a water tank, a booster pump and a cooling flow channel in the roller to realize the circulation of the coolant. Some devices improve the cooling efficiency by adding auxiliary cooling equipment such as a freezer and an air conditioner. Its core is to absorb the heat transferred from the printed matter through the flow of the coolant in the roller, and then reduce the temperature of the coolant through an external cooling device. However, the existing water-cooled devices have obvious defects: the heat exchange of the coolant in the roller is insufficient, and the cooling efficiency is low; there is a lack of an effective filtering system, resulting in impurities in the coolant wearing the equipment; the water temperature control is inaccurate, and it is difficult to meet the requirements of different printing speeds and ambient temperatures; particularly prominent is that when the machine stops, the surface temperature of the cooling roller is lower than the ambient temperature, and water vapor is easily condensed, resulting in wetting of the paper tape, paper breakage and even equipment corrosion.

[0003] In summary, the disadvantages of the prior art are: the natural limitation of single-sided cooling of the air-cooled type leads to insufficient cooling effect, while the water-cooled type has an unreasonable flow channel design, slow coolant flow, and low heat exchange efficiency, and cannot meet the rapid cooling requirements during high-speed printing (such as more than 15,000 sheets per hour). The existing water-cooled devices cannot effectively drain the coolant in the roller when the machine stops, and the residual coolant keeps the roller at a low temperature, and when it contacts the ambient air, condensation water is formed, which will not only wet the paper tape and cause paper breakage, but also cause corrosion of the roller and related components, shortening the service life of the equipment.

[0004] At present, there is no mature solution for the double-sided cooling requirements during the high-speed paper feeding process of web commercial printing machines, as well as the problems of condensation paper breakage and equipment corrosion when the machine stops. In the prior art, there are still technical blanks in the design of the cooling roller flow channel structure and the optimization of the automatic water control. There is an urgent need for a new type of post-print cooling device that can take into account efficient cooling, automatic control and anti-condensation functions. Summary of the Invention

[0005] The first object of the present invention is to provide a post-printing cooling device for an offset printing machine, which solves the technical problems of low cooling efficiency in the existing post-printing cooling device for an offset printing machine and the easy occurrence of dew condensation and paper breakage and equipment rust due to residual coolant during shutdown.

[0006] The second object of the present invention is to provide a post-printing cooling method for an offset printing machine.

[0007] The first technical solution adopted by the present invention is that a post-printing cooling device for an offset printing machine includes a cooling system and a plurality of cooling rollers; the cooling rollers are hollow rotating bodies, and spiral flow channels adapted to the rotation direction of the cooling rollers and the liquid flow direction are provided on the inner walls of the cooling rollers. Fluid inlets and outlets are respectively provided at both ends of the cooling rollers and communicated with the inner cavity of the cooling rollers; the cooling system includes a reversing valve, a circulation circuit and a liquid storage unit. The reversing valve is controlled to switch the flow direction of the coolant so that the coolant circulates between the liquid storage unit and the cooling rollers through the circulation circuit, and a one-way check assembly is provided in the circulation circuit to prevent backflow. The characteristics of the first technical solution of the present invention are as follows: The spiral flow channel is a left-handed or right-handed spiral guide groove matching the rotation direction of the cooling roller. The two ends of the cooling roller are respectively a left shaft head and a right shaft head. An inlet is opened on the right shaft head, and an outlet is opened on the left shaft head. The inlet and the outlet are communicated with the inner cavity of the cooling roller; The reversing valve is an electric three-way ball valve, and the liquid storage unit is a cooling water tank. The first end of the electric three-way ball valve is communicated with the inlet through a first pipeline, the second end of the electric three-way ball valve is communicated with the cooling water tank through a second pipeline, a booster pump is provided in the cooling water tank, and the third end of the electric three-way ball valve is communicated with the booster pump through a third pipeline; the outlet is communicated with the cooling water tank through a fourth pipeline; a one-way check assembly is installed on the fourth pipeline; wherein, the first pipeline, the third pipeline and the fourth pipeline form a first circulation circuit, and the second pipeline and the third pipeline form a second circulation circuit.

[0008] The spiral angle of the spiral guide groove is 30°-60°, the groove depth is 2mm-5mm, and the pitch is 10mm-20mm.

[0009] The one-way check assembly is a check valve, and the check valve is a spring-type one-way valve, and the opening pressure of the valve flap is 0.1-0.2MPa. The cooling roller is made of stainless steel. The left shaft head and the right shaft head at both ends of the cooling roller are installed on the frame through bearings. A pulley is installed at the right shaft head, and the pulley is connected with the output shaft of the driving motor through a belt.

[0010] A flow meter and a thermometer are installed on the first pipeline, a refrigerator is installed in the cooling water tank, and the flow meter, the thermometer, the refrigerator and the booster pump are signal-connected to the control system of the offset printing machine.

[0011] The control system adopts a PLC or an industrial computer.

[0012] The second technical solution adopted by the present invention is a post-printing cooling method for an offset printing machine, which uses the above-mentioned post-printing cooling device for an offset printing machine, and includes the following steps: S1: Set the target flow rate and temperature of the coolant according to the operating parameters of the offset printing machine; S2: Control the coolant to be driven by a booster pump through an electric three-way ball valve to form a circulation between the cooling roller and the cooling water tank; S3: The flow meter and thermometer real-time feedback data, dynamically adjust the output of the booster pump and the operation of the refrigerator, so that the coolant parameters are maintained within the target range; S4: Automatically switch the electric three-way ball valve to cut off the cooling roller path when stopping, and use the rotational inertia of the cooling roller to drain the residual medium into the cooling water tank.

[0013] The characteristics of the second technical solution of the present invention are as follows: In S1, the target parameters of the coolant are: when the printing speed of the offset printing machine > 15,000 sheets / hour: the flow rate is 10 L / min - 12 L / min, and the temperature is 22 ± 2 °C; when the printing speed of the offset printing machine ≤ 15,000 sheets / hour: the flow rate is 8 L / min - 10 L / min, and the temperature is 24 ± 2 °C.

[0014] Compared with the prior art, the beneficial effects of the present invention are: Compared with the prior art, the present invention accelerates the flow of the coolant through the spiral diversion grooves inside the cooling roller, significantly improves the heat exchange efficiency, and meets the requirements of double-sided cooling for high-speed printing; the waterway system is equipped with an electric reversing valve and a check valve, and the coolant inside the roller is automatically drained when the power is off, solving the problems of paper breakage due to condensation and equipment corrosion during shutdown. Brief Description of the Drawings

[0015] Figure 1 is a schematic structural diagram of the post-printing cooling device for an offset printing machine of the present invention; Figure 2 is a schematic structural diagram of the cooling roller in the post-printing cooling device for an offset printing machine of the present invention; Figure 3 is a schematic diagram of the pipeline connection structure of the electric three-way ball valve in the post-printing cooling device for an offset printing machine of the present invention; Figure 4 is a schematic diagram of the paper feeding route of the post-printing cooling device for an offset printing machine of the present invention; Figure 5 is a schematic diagram of the flow path between the cooling rollers in the post-printing cooling device for an offset printing machine of the present invention.

[0016] In the figure: 1. Cooling roller, 1-1. Left shaft head, 1-2. Right shaft head, 1-3. Spiral diversion groove, 2. Electric three-way ball valve, 3. Cooling water tank, 4. Booster pump, 5. Refrigerator, 6. Flow meter, 7. Thermometer, 8. First pipeline, 9. Second pipeline, 10. Third pipeline, 11. Fourth pipeline, 12. Check valve, 13. Frame, 14. Paper. Detailed implementation manners

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0018] Embodiment 1 As Figures 1-5 shown, the post-printing cooling device of the offset printing machine disclosed in this embodiment includes a cooling system and a plurality of cooling rollers 1; the cooling roller 1 is a hollow rotating body, and a spiral flow channel adapted to the rotation direction of the cooling roller 1 and the liquid flow direction is provided on the inner wall of the cooling roller 1. Fluid inlets and outlets are respectively provided at both ends of the cooling roller 1 and are communicated with the inner cavity of the cooling roller 1; the cooling system includes a reversing valve, a circulation loop and a liquid storage unit. The reversing valve is controlled to switch the flow direction of the coolant, so that the coolant circulates between the liquid storage unit and the cooling roller 1 through the circulation loop. A one-way check component is provided in the circulation loop to prevent backflow.

[0019] In this embodiment, the cooling roller 1 is a hollow rotating body, and a spiral flow channel adapted to the rotation direction is provided on the inner wall to accommodate the coolant and guide its flow. When rotating, the "spiral pump effect" is generated through the spiral flow channel to accelerate the flow of the coolant and strengthen heat exchange; when the machine stops, the residual medium is emptied by using the structural characteristics of the flow channel. The reversing valve is controlled to switch the flow direction of the coolant. When the machine is started, the cooling roller 1 is connected to the circulation loop, so that the medium enters the cooling roller 1 to participate in heat exchange; when the machine stops, the passage of the cooling roller 1 is cut off, and the medium is diverted to the bypass loop to avoid water accumulation in the cooling roller 1. The circulation loop and the liquid storage unit form a closed-loop circulation path for the coolant. The liquid storage unit stores the medium and provides the circulation power (such as an internal pump body) to ensure the continuous flow of the medium; a one-way check component is integrated in the loop to prevent the backflow of the medium. The one-way check component is installed in the loop and only allows the coolant to flow in one direction, preventing the medium in the bypass loop from flowing back into the cooling roller 1 when the machine stops, and cooperating with the spiral flow channel to achieve residue-free emptying.

[0020] Dynamic cooling stage: The reversing valve connects the passage of the cooling roller 1, and the coolant in the liquid storage unit enters the spiral flow channel under the drive of power, and flows at a high speed along the spiral path with the rotation of the cooling roller 1, fully absorbing the heat on the surface of the cooling roller 1 (from the printed matter) to achieve efficient heat exchange; Shutdown protection stage: The reversing valve switches the flow direction to cut off the passage of the cooling roller 1. The cooling roller 1 continues to rotate due to inertia, and the spiral flow channel uses centrifugal force and gravity to discharge the residual medium into the liquid storage unit through the one-way check component, avoiding the retention of the medium on the roller body.

[0021] The present invention realizes the efficient circulating heat exchange of the coolant during the printing process and the automatic drainage and anti-condensation during shutdown through the cooperation of the spiral flow channel and the commutation control, improving the cooling efficiency and stability of the equipment.

[0022] Embodiment 2 On the basis of Embodiment 1, the spiral flow channel is a left-handed or right-handed spiral diversion groove 1-3 matching the rotation direction of the cooling roller 1. The two ends of the cooling roller 1 are respectively a left shaft head 1-1 and a right shaft head 1-2. An inlet is opened on the right shaft head 1-2, and an outlet is opened on the left shaft head 1-1; The commutation valve is an electric three-way ball valve 2, and the liquid storage unit is a cooling water tank 3. The first end of the electric three-way ball valve 2 is connected to the inlet through a first pipeline 8, the second end of the electric three-way ball valve 2 is connected to the cooling water tank 3 through a second pipeline 9, a booster pump 4 is arranged in the cooling water tank 3, and the third end of the electric three-way ball valve 2 is connected to the booster pump through a third pipeline 10; The outlet is connected to the cooling water tank 3 through a fourth pipeline 11; A one-way check assembly is installed on the fourth pipeline 11; Among them, the first pipeline 8, the third pipeline 10 and the fourth pipeline 11 form a first circulation loop, and the second pipeline 9 and the third pipeline 10 form a second circulation loop.

[0023] This embodiment provides a post-printing cooling device for an offset printing machine, and the core components are a cooling roller 1 and a cooling system. The cooling roller 1 adopts a hollow cylindrical structure, and a left-handed or right-handed spiral diversion groove 1-3 matching the rotation direction is arranged on the inner wall. Inlets and outlets are respectively opened on the left shaft head 1-1 and the right shaft head 1-2 to realize the spiral path flow of the coolant in the cooling roller 1. The cooling system is connected to the cooling water tank 3 and the cooling roller 1 through an electric three-way ball valve 2 to form a circulation loop, and the check valve 12 prevents the reverse flow of the coolant. The "spiral pump effect" is utilized to accelerate the flow of the coolant, enabling the coolant to fully contact the inner wall of the cooling roller 1 and improving the heat exchange efficiency; when the machine stops, the coolant is completely drained by means of the spiral structure. Controlled by the electrical signal of the control system, the inlet of the cooling roller 1 is connected when the machine is started, and the flow direction is switched when the power is off so that the coolant enters the bypass loop for circulation, avoiding the accumulation of water in the cooling roller 1. Ensure the one-way flow of the coolant and prevent the liquid in the return pipe (the fourth pipeline 11) from flowing back to the cooling roller 1 when the machine stops. Achieve the purpose and advantages: Through the spiral flow channel design and the automatic control of the circulating water path, solve the problems of insufficient heat exchange in the existing water-cooled devices and condensation and rust caused by the residual coolant during shutdown, realize efficient double-sided cooling during high-speed printing, and improve the stability of the equipment. Solve the problems of the existing technology: Overcome the defects of the unreasonable design of the traditional water-cooled roller flow channel and the slow flow of the coolant, avoid the formation of condensed water when the machine stops, and prevent the paper tape from being wetted, the paper from breaking, and the equipment from rusting.

[0024] In this embodiment, as Figure 4 shown, the four cooling rollers 1 are successively the first cooling roller 1, the second cooling roller 1, the third cooling roller 1, and the fourth cooling roller 1 along the direction from top to bottom and from left to right. The coolant flow directions of the first cooling roller 1 and the second cooling roller 1 are the same, and the coolant flow directions of the third cooling roller 1 and the fourth cooling roller 1 are the same. Therefore, the corresponding relationships between the left shaft head, the right shaft head, the water inlet, and the water outlet are not fixed. In addition, the spiral guide groove 1-3 in the cooling roller 1 is related to the rotation direction of the cooling roller 1 and also to the liquid path flow direction. According to the "spiral pump effect", it can be determined that the first cooling roller 1 and the fourth cooling roller 1 are right-handed, and the second cooling roller 1 and the third cooling roller 1 are left-handed.

[0025] Embodiment 3 Based on Embodiment 2, the spiral angle of the spiral guide groove 1-3 is 30°-60°, the groove depth is 2mm-5mm, and the pitch is 10mm-20mm.

[0026] This embodiment defines the specific parameters of the spiral guide groove 1-3: spiral angle 30°-60°, groove depth 2mm-5mm, pitch 10mm-20mm. The spiral angle optimizes the water flow propulsion efficiency, and the groove depth and pitch balance the flow resistance and the contact area to ensure that the coolant forms a stable spiral flow in the cooling roller 1 and strengthens the "spiral pump effect". Select the spiral direction of the guide groove according to the rotation direction of the cooling roller 1 to make the centrifugal force and the spiral thrust cooperate to maximize the water flow speed and the drainage effect. Precisely control the coolant flow parameters to form efficient heat exchange during high-speed rotation, and at the same time ensure that the residual coolant is quickly drained after shutdown to avoid long-term immersion of the cooling roller 1. Solve the problem of coolant retention caused by the non-spiral structure of the traditional water-cooled roller flow channel, and improve the heat exchange efficiency by more than 30% through parameter optimization, and shorten the drainage time by 50%.

[0027] Embodiment 4 Based on Embodiment 2, the one-way check valve assembly is the check valve 12, and the check valve 12 is a spring-type one-way valve, and the opening pressure of the valve flap is 0.1-0.2 MPa. In this embodiment, the check valve 12 adopts a spring-type one-way valve, and the opening pressure of the valve flap is 0.1-0.2 MPa. The valve flap is kept closed by the spring force and opens when the forward flow pressure of the coolant exceeds 0.1-0.2 MPa, and automatically closes during reverse flow to ensure the one-way flow of the water path. When the power is off, the electric three-way ball valve 2 cuts off the water inlet of the cooling roller 1, and the check valve 12 prevents the liquid in the return pipe from flowing back, and cooperates with the spiral guide groove 1-3 to achieve residue-free drainage. Realize reliable reverse flow protection at low cost, avoid coolant backflow to the cooling roller 1 during shutdown, ensure the drainage effect, and extend the equipment life. Replace the traditional design without a one-way valve, eliminate the problem of water accumulation in the cooling roller 1 caused by coolant backflow, and eliminate the hidden danger of condensation during shutdown from the structure.

[0028] Embodiment 5 Based on Embodiment 2, the cooling roller 1 is made of stainless steel. The left shaft head 1-1 and the right shaft head 1-2 at both ends of the cooling roller 1 are installed on the frame 13 through bearings. A pulley is installed at the right shaft head 1-2, and the right shaft head 1-2 is connected to the output shaft of the driving motor through a belt. In this embodiment, the cooling roller 1 is made of stainless steel. A pulley is installed at the right shaft head 1-2, and the pulley is connected to the output shaft of the driving motor through a belt. The stainless steel material is corrosion-resistant and can adapt to the long-term contact environment of the coolant, avoiding the corrosion of the cooling roller 1 and affecting the cooling effect. The belt connection between the pulley and the motor ensures the stable rotation of the cooling roller 1, transmits the driving force of the motor, and enables the spiral diversion groove 1-3 to effectively exert the "spiral pump effect". It improves the structural strength and corrosion resistance of the cooling roller 1, ensures the stability during high-speed rotation, and provides hardware support for the efficient operation of the spiral flow channel. It solves the problems of channel blockage and reduced transmission efficiency caused by the easy rusting of the traditional cooling roller material and poor installation stability, and extends the equipment maintenance cycle.

[0029] Embodiment 6 Based on Embodiment 2, a flow meter 6 and a thermometer 7 are installed on the first pipeline, and a refrigerator 5 is installed in the cooling water tank 3. The flow meter 6, the thermometer 7, the refrigerator 5 and the booster pump 4 are signal-connected to the control system of the offset printing machine.

[0030] In this embodiment, the first pipeline 8 is provided with a flow meter 6 and a thermometer 7, and the cooling water tank 3 is internally provided with a refrigerator 5, all of which are signal-connected to the control system. The flow meter 6 and the thermometer 7 monitor the flow rate and temperature of the coolant in real time and feedback them to the control system to form a closed-loop control. The refrigerator 5 and the booster pump 4 adjust the temperature of the coolant (refrigerator) and the flow rate (rotation speed of the booster pump) according to the control instructions of the control system to adapt to different printing speed requirements. Through automatic monitoring and adjustment, the coolant parameters are accurately controlled, solving the problems of inaccurate water temperature control and unstable flow rate in the prior art, and realizing the adaptive operation of the cooling system. It replaces the manual adjustment mode, avoids the cooling efficiency fluctuation caused by the change of environmental temperature or printing speed, and ensures that the temperature is stable within ±2°C during high-speed printing.

[0031] Furthermore, the control system adopts a PLC or an industrial computer.

[0032] In this embodiment, the control system adopts a PLC or an industrial computer. The PLC / industrial computer receives the sensor signals (flow rate, temperature, speed), processes them and outputs control instructions (adjusting the electric valve, pump speed, refrigerator), realizing the full-system automation. Using a mature industrial control platform, it ensures the reliability and flexibility of the control logic, supports multi-parameter real-time monitoring and complex algorithm operations.

[0033] The present invention also discloses a post-printing cooling method for an offset printing machine, which adopts the post-printing cooling device of the offset printing machine as in Embodiment 6, including the following steps: S1: Set the target flow rate and temperature of the coolant according to the operating parameters of the offset printing press; Specifically: According to the real-time operating parameters of the offset printing press (such as printing speed, paper thickness, ink type, etc.), preset the target flow rate and temperature range of the coolant (coolant) through the control system. For high-speed printing conditions (>15,000 sheets / hour), set higher cooling intensity parameters (such as a flow rate of 10 - 12 L / min and a temperature of 22 ± 2°C); when in low-speed conditions, automatically switch to energy-saving parameters (such as a flow rate of 8 - 10 L / min and a temperature of 24 ± 2°C) to form a differential cooling strategy.

[0034] S2: Control the coolant to form a cycle between the cooling roller 1 and the cooling water tank 3 driven by the booster pump 4 through the electric three-way ball valve 2, and use the spiral flow channel in the cooling roller 1 to achieve efficient heat exchange; Specifically: The control system drives the electric three-way ball valve 2 to connect the cooling roller 1 passage, and the booster pump 4 pumps the coolant in the cooling water tank 3 to the cooling roller 1. The coolant enters the inner wall spiral flow channel through the inlet of the cooling roller 1. Under the spiral pump effect generated by the rotation of the cooling roller 1, it accelerates along the spiral path and fully exchanges heat with the inner wall of the cooling roller 1, absorbs the heat transferred from the printed matter, and then returns to the cooling water tank 3 through the outlet to form a closed-loop circulation circuit.

[0035] S3: Dynamically adjust the output of the booster pump 4 and the operation of the cooler 5 by means of the real-time feedback data of the flow meter 6 and the thermometer 7, so that the coolant parameters are maintained within the target range; Specifically: The flow meter 6 and the thermometer 7 collect the flow rate and temperature data of the coolant in real time and feedback them to the control system to form a closed-loop control: If the flow rate is 10% lower than the target value, the control system automatically increases the output power of the power device (such as increasing the rotation speed of the booster pump 4) until the flow rate reaches the standard; If the temperature is higher than the target upper limit (such as 28°C), start the cooler 5 to cool the coolant in the cooling water tank 3; when it is lower than the target lower limit (such as 20°C), automatically turn off the temperature control device to ensure that the coolant parameters are stable within the preset range.

[0036] S4: When shutting down, automatically switch the electric three-way ball valve 2 to cut off the cooling roller 1 passage, and use the rotational inertia of the cooling roller 1 to drain the residual medium to the cooling water tank 3 through the check valve 12 to prevent backflow and condensation.

[0037] Specifically, when the offset press receives a shutdown instruction, the control system immediately switches the electric three-way ball valve 2 to cut off the passage of the cooling roller 1 and divert the coolant to the bypass circuit for circulation. Utilizing the rotational inertia of the cooling roller 1 (lasting for 2 - 3 revolutions), the centrifugal force generated by the spiral flow channel and the gravity work together to completely drain the residual coolant in the cooling roller 1 through the water outlet and the check valve 12 into the cooling water tank 3. The check valve 12 prevents the medium from flowing back, avoiding the condensation of water vapor on the surface of the cooling roller 1 due to the low temperature of the residual medium after shutdown, and simultaneously completing the equipment shutdown protection.

[0038] In this embodiment, based on the device of Embodiments 1 - 6, the cooling method includes steps such as parameter setting, circulation control, real-time adjustment, and shutdown drainage. The electric three-way ball valve 2 and the check valve 12: switch the flow direction during shutdown and prevent backflow, cooperate with the inertial rotation of the cooling roller 1, and drain the residual liquid through the spiral diversion groove 1 - 3. The flow meter 6, the thermometer 7, and the control system: dynamically adjust the rotation speed of the booster pump 4 and the start and stop of the cooler 5 to ensure that the coolant parameters meet the printing speed requirements. Through a standardized process, full-cycle automatic control of the cooling system is achieved, ensuring efficient cooling and anti-condensation functions throughout the process from startup to shutdown. Solve the problems of coolant retention after shutdown and lag in manual parameter adjustment of traditional water-cooling devices, achieve double-sided uniform cooling during high-speed printing (>15,000 sheets / hour), and complete drainage within 3 seconds after shutdown.

[0039] Further, the target parameters of the coolant in S1 are as follows: when the printing speed of the offset press > 15,000 sheets / hour: the flow rate is 10 L / min - 12 L / min, and the temperature is 22 ± 2 °C; when the printing speed of the offset press ≤ 15,000 sheets / hour: the flow rate is 8 L / min - 10 L / min, and the temperature is 24 ± 2 °C.

[0040] In this embodiment, different target parameters of the coolant are set according to the printing speed: at high speed, the flow rate is 10 - 12 L / min and the temperature is 22 ± 2 °C; at low speed, the flow rate is 8 - 10 L / min and the temperature is 24 ± 2 °C. According to the preset parameter range, the rotation speed of the booster pump 4 (to control the flow rate) and the power of the cooler 5 (to control the temperature) are automatically adjusted to achieve hierarchical cooling. Provide precise cooling capacity for different printing speeds, enhance the cooling ability at high speed to avoid insufficient ink curing, save energy and reduce consumption at low speed, and improve the energy efficiency ratio of the system. Change the "one-size-fits-all" control mode of the traditional cooling system, avoid problems such as insufficient cooling causing paper deformation at high speed and excessive cooling wasting energy at low speed, and adapt to diverse printing requirements.

[0041] Finally, it should also be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising said element.

[0042] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other.

[0043] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. Post-press cooling device for offset printing machine, characterized in that: It includes a cooling system and multiple cooling rollers (1); the cooling rollers (1) are hollow rotating bodies, and the inner wall of the cooling rollers (1) is provided with spiral flow channels adapted to the rotation direction of the cooling rollers (1) and the liquid flow direction of the liquid path. Fluid inlets and outlets are respectively arranged at both ends of the cooling rollers (1) and are communicated with the inner cavity of the cooling rollers (1); the cooling system includes a reversing valve, a circulation loop and a liquid storage unit. The reversing valve is controlled to switch the flow direction of the coolant, so that the coolant circulates between the liquid storage unit and the cooling rollers (1) through the circulation loop, and a one-way check assembly is arranged in the circulation loop to prevent backflow.

2. The post-printing cooling device of an offset printing machine according to claim 1, wherein: The spiral flow channel is a left-handed or right-handed spiral diversion groove (1-3) matching the rotation direction of the cooling roller (1). The two ends of the cooling roller (1) are respectively a left shaft head (1-1) and a right shaft head (1-2). An inlet is opened on the right shaft head (1-2), and an outlet is opened on the left shaft head (1-1). The inlet and the outlet are communicated with the inner cavity of the cooling roller (1); The reversing valve is an electric three-way ball valve (2), and the liquid storage unit is a cooling water tank (3). The first end of the electric three-way ball valve (2) is communicated with the inlet through a first pipeline (8), the second end of the electric three-way ball valve (2) is communicated with the cooling water tank (3) through a second pipeline (9), a booster pump (4) is arranged in the cooling water tank (3), and the third end of the electric three-way ball valve (2) is communicated with the booster pump through a third pipeline (10); the outlet is communicated with the cooling water tank (3) through a fourth pipeline (11); a one-way check assembly is installed on the fourth pipeline (11); wherein, the first pipeline (8), the third pipeline (10) and the fourth pipeline (11) form a first circulation loop, and the second pipeline (9) and the third pipeline (10) form a second circulation loop.

3. The post-printing cooling device of the offset printing machine according to claim 2, characterized in that: The spiral angle of the spiral diversion groove (1-3) is 30°-60°, the groove depth is 2mm-5mm, and the pitch is 10mm-20mm.

4. The post-printing cooling device of the offset printing machine according to claim 2, characterized in that: The one-way check assembly is a check valve (12), and the check valve (12) is a spring-type one-way valve, and the opening pressure of the valve flap is 0.1-0.2MPa.

5. The post-printing cooling device of the offset printing machine according to claim 2, characterized in that: The cooling roller (1) is made of stainless steel. The left shaft head (1-1) and the right shaft head (1-2) at both ends of the cooling roller (1) are installed on the frame (13) through bearings. A pulley is installed at the right shaft head (1-2), and the pulley is connected with the output shaft of the driving motor through a synchronous belt.

6. The post-printing cooling device of the offset printing machine according to claim 2, characterized in that: A flow meter (6) and a thermometer (7) are installed on the first pipeline, a refrigerator (5) is installed in the cooling water tank (3), and the flow meter (6), the thermometer (7), the refrigerator (5) and the booster pump (4) are signal-connected to the control system of the offset printing machine.

7. The post-printing cooling device of an offset printing machine according to claim 6, wherein: The control system adopts a PLC or an industrial computer.

8. The post-printing cooling method of an offset printing machine, using the post-printing cooling device of the offset printing machine as described in claim 7, characterized in that, It includes the following steps: S1: Set the target flow rate and temperature of the coolant according to the operating parameters of the offset printing machine; S2: Control the coolant to be driven by the booster pump (4) through the electric three-way ball valve (2) to form a circulation between the cooling roller (1) and the cooling water tank (3); S3: The flowmeter (6) and the thermometer (7) provide real-time feedback of data to dynamically adjust the output of the booster pump (4) and the operation of the cooler (5), so as to maintain the coolant parameters within the target range. S4: When shutting down, the electric three-way ball valve (2) is automatically switched to cut off the passage of the cooling roller (1), and the residual medium is emptied into the cooling water tank (3) by using the rotational inertia of the cooling roller (1).

9. The post-printing cooling method of the offset printing machine according to claim 8, wherein: In S1, the target parameters of the coolant are as follows: when the printing speed of the offset printing machine > 15,000 sheets / hour: the flow rate is 10 L / min - 12 L / min, and the temperature is 22 ± 2°C; when the printing speed of the offset printing machine ≤ 15,000 sheets / hour: the flow rate is 8 L / min - 10 L / min, and the temperature is 24 ± 2°C.

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