Intelligent control system for a letterpress printing process

Abstract

The utility model discloses an intelligent control system of letterpress printing process, including central control unit, man -machine interface is connected with central control unit communication, pressure intelligent regulation module is connected with central control unit, and pressure intelligent regulation module includes pressure sensor group for real -time detection between actual pressure of plate roll and impression roll and receives pressure servo driver of central control unit instruction and drives pressure regulation mechanism, ink supply intelligent control module is connected with central control unit, and the module includes visual detection device for on -line collection printed matter image and calculates ink area density information. In conclusion, the utility model overcomes the deficiency of prior art, realizes the fundamental change of letterpress printing from depending on manual experience to automation, digitization through the integrated pressure, ink supply and the intelligent closed loop control of register, has higher social use value and application prospect.

Description

Technical Field

[0001] This utility model relates to the field of letterpress printing technology, and in particular to an intelligent control system for letterpress printing process. Background Technology

[0002] Letterpress printing, as a representative of direct printing, holds an irreplaceable position in high-end packaging, trademarks, bookbinding, and specialty printing due to its thick ink layers, vibrant colors, and strong three-dimensional effect. However, its printing process involves the complex interaction of several key process parameters, and traditional control methods have inherent defects.

[0003] 1) The pressure between the printing roller and the impression roller is the key to determining the quality of the printed product and the life of the printing plate. At present, most of them use manual adjustment of the eccentric sleeve or wedge mechanism, which relies on the operator's feel and experience. This has problems such as low adjustment accuracy, poor consistency, and easy damage to the printing plate due to excessive pressure or blurry printing due to insufficient pressure.

[0004] 2) Delayed and crude ink supply control: Ink volume adjustment relies on the operator manually adjusting the ink keys after observing the printed product, resulting in slow response and an inability to achieve precise control over the ink area. Color differences are unavoidable when producing the same product in different batches or on different machines.

[0005] 3) Low efficiency of registration correction: The registration process requires manual identification of the marking lines and manual adjustment, which is time-consuming and labor-intensive, and it is difficult to achieve dynamic real-time correction in high-speed printing.

[0006] Therefore, there is an urgent need for an intelligent control system that can realize intelligent, efficient and high-quality letterpress printing processes. Utility Model Content

[0007] In order to solve the problems mentioned in the background art, the present invention provides an intelligent control system for letterpress printing process.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] The system includes: a central control unit; a human-machine interface (HMI) communicating with the central control unit; a pressure intelligent adjustment module connected to the central control unit, comprising a pressure sensor group for real-time detection of the actual pressure between the printing roller and the impression roller, and a pressure servo driver that receives commands from the central control unit and drives the pressure adjustment mechanism; an ink supply intelligent control module connected to the central control unit, comprising a visual inspection device for online acquisition of printed images and calculation of ink density information, and multiple ink key actuators that receive commands from the central control unit to adjust the ink key opening; an automatic registration correction module connected to the central control unit, comprising a registration sensor for detecting the position of the registration mark line, and a registration motor that receives commands from the central control unit to adjust the phase of the printing roller; and a data management and communication module integrated with the central control unit for storing printing formula data and communicating with external systems.

[0010] Preferably, the pressure sensor group is a thin-film pressure sensor or a piezoelectric force sensor array distributed and installed on the printing roller bearing seat.

[0011] Preferably, the visual inspection device includes a CCD or CMOS industrial camera, a uniform light source providing illumination for the CCD or CMOS industrial camera, and a computer unit for image processing, wherein the CCD or CMOS industrial camera is mounted above or to the side of the printed material's travel path.

[0012] Preferably, the pressure regulating mechanism is an eccentric sleeve, wedge mechanism, or linear module driven by a servo motor.

[0013] Preferably, the central control unit is a programmable logic controller or an industrial computer.

[0014] Compared with the prior art, the beneficial effects of this utility model are:

[0015] 1. It achieves intelligent and automated operation, reducing reliance on manual experience: By coordinating the three closed-loop control systems of pressure, ink supply, and registration through a central control unit, the complex debugging process that traditionally relied on operator feel and experience is transformed into an intelligent process that can automatically call up formulas, execute automatically, and continuously optimize. This not only significantly reduces the labor intensity and technical threshold for operators, but also effectively avoids printing quality instability caused by differences in personnel skills or fluctuations in their condition.

[0016] 2. Significantly improves production efficiency and material utilization: The system's "one-click initialization" function reduces the job changeover and debugging time from tens of minutes or even hours in the traditional mode to minutes, significantly improving equipment utilization. At the same time, precise initial settings and continuous process control minimize debugging waste and quality defects in the production process, thereby significantly reducing waste of materials such as paper and ink and improving material utilization.

[0017] 3. Ensures exceptional consistency and stability in printing quality: A closed-loop control mechanism based on real-time sensor feedback proactively and promptly compensates for interference caused by changes in ink viscosity, fluctuations in ambient temperature and humidity, machine vibration, and uneven substrate thickness. This ensures that the ink uniformity, registration accuracy, and printing pressure of the printed products remain highly consistent throughout the entire printing process, regardless of duration or batch sequence, achieving reproducible high-quality output that surpasses manual control.

[0018] In summary, this utility model overcomes the shortcomings of the prior art. By integrating intelligent closed-loop control of pressure, ink supply and registration, it realizes a fundamental transformation of letterpress printing from relying on manual experience to automation and digitalization, and has high social use value and application prospects. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall hardware connection and signal flow of the system of this utility model.

[0021] Figure 2 This is a schematic diagram illustrating the installation and working principle of a pressure intelligent regulation module in a specific embodiment.

[0022] Figure 3 This is a schematic diagram showing the layout and working principle of the ink supply intelligent control module in a specific embodiment. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0024] Example 1

[0025] Reference Figure 1 An intelligent control system for letterpress printing process includes a central control unit 1, a human-machine interface 2, a pressure intelligent adjustment module 3, an ink supply intelligent control module 4, an automatic registration correction module 5, and a data management and communication module 9.

[0026] The central control unit 1 serves as the core of the system. It employs an industrial-grade programmable logic controller or industrial computer (in this example, a high-performance PLC, such as the Siemens S7-1500 series, is selected). It has a built-in control algorithm to process all sensor data, perform logical operations, and output control commands. The data management and communication module 9 is integrated into the central control unit 1. It includes an SD memory card for storing recipes and is equipped with a PROFINET interface to connect to the factory's MES system.

[0027] The human-machine interface 2 is an industrial touch screen that communicates with the central control unit 1 via Ethernet. It is used to input process parameters such as target pressure value, target ink density / area ratio, and registration tolerance, and to display the operating status of each module, sensor data, and alarm information in real time, as well as provide a formula management interface.

[0028] The intelligent pressure adjustment module 3 includes a pressure detection unit and a pressure execution unit. The pressure detection unit consists of an array of high-precision pressure sensors 31 (in this embodiment, TekScan thin-film pressure sensors are used) distributed on the bearing seats of the printing roller 6 and the impression roller 7, used to collect linear pressure values ​​of each area in real time. The pressure execution unit consists of a pressure servo driver 32 and a precision pressure adjustment mechanism 33 connected to it. The pressure adjustment mechanism 33 can be an eccentric sleeve, a wedge mechanism, or a linear module driven by a servo motor. The central control unit 1 receives the signal from the pressure sensor 31, compares it with the set value, and drives the pressure servo driver 32 through a PID or fuzzy PID algorithm to achieve precise closed-loop control of the printing pressure.

[0029] Preferably, in this embodiment, the pressure regulating mechanism 33 employs a precision wedge mechanism driven by a servo motor. During operation, the operator sets the target pressure value (e.g., 2000N) on the HMI. The central control unit 1 controls the pressure servo driver 32 to drive the servo motor, pushing the wedge to move the printing roller towards the printing roller 6. The pressure sensor 31 provides real-time feedback of the pressure signal to the central control unit 1. The PID control program inside the central control unit 1 continuously compares the set value with the feedback value, outputting control signals to adjust the rotation angle and speed of the servo motor until the actual pressure stabilizes within a very small error range near the target value.

[0030] The intelligent ink supply control module 4 includes a vision detection unit and an ink volume execution unit. The vision detection unit is a vision detection device 41, which includes a CCD or CMOS industrial camera mounted at the printing inspection station, a matching uniform light source, and an image processing card. It is used to capture printed images online and calculate the ink density or dot area ratio of each ink zone in real time using image processing algorithms. The ink volume execution unit consists of multiple high-precision ink key actuators 42, each corresponding to an ink zone. It receives instructions from the central control unit 1 and precisely controls its opening. The central control unit 1 compares the ink color information fed back by the vision detection unit with the target value and dynamically adjusts each ink key actuator 42 to achieve online, closed-loop, and zoned fine-grained control of the ink supply.

[0031] Preferably, in this embodiment, a CMOS industrial camera captures the printed pattern on the substrate 8 at a fixed frequency. The acquired images are transmitted via gigabit Ethernet to an industrial computer equipped with dedicated image processing software, which analyzes the grayscale value of each ink zone or calculates the dot area ratio in real time. If the density of the third ink zone is detected to be lower than the target value, the central control unit 1 sends a pulse signal to the ink key actuator 42 (high-precision servo motor) controlling that zone, causing it to fine-tune the ink key 43, increasing the ink supply gap, thereby increasing the ink volume in that zone, forming a continuous closed-loop adjustment.

[0032] The automatic registration correction module 5 includes a registration detection unit and a registration execution unit. The registration detection unit is a registration sensor 51 (using a high-resolution photoelectric sensor or a dedicated vision sensor) used to accurately identify the position of the registration marks on the printed material. The registration execution unit is a registration motor 52 used to drive the circumferential or axial position of the printing roller 6. The central control unit 1 calculates the current registration error based on feedback from the registration detection unit and controls the registration servo motor to compensate, thus achieving automatic registration.

[0033] Preferably, in this embodiment, the registration sensor 51 (using a photoelectric color sensor from SICK) detects the registration mark lines on the edge of the substrate. When a misalignment of the mark line is detected, the registration sensor 51 sends a signal to the central control unit 1. The central control unit 1 calculates the number of pulses required for compensation based on the offset and direction, and drives the registration motor 52 (servo motor) to rotate the transmission mechanism (such as a differential gear mechanism) of the printing roller 6 in a small circumferential direction, thereby correcting the position of the image and text.

[0034] Working principle: Pressure sensors 31 distributed on the bearing housing collect the current actual pressure value in real time. Central control unit 1 reads and the target pressure value Calculate the pressure deviation The PID control program inside the central control unit 1 is based on the pressure deviation. The size and direction are calculated to generate a control signal, which is sent to the pressure servo driver 32. The driver drives the servo motor, which finely adjusts the angle of the eccentric sleeve through the worm gear pair, thereby changing the position of the printing roller 6. Towards The process continues until the deviation approaches zero. This process is repeated to counteract interference such as machine vibration and substrate thickness fluctuations.

[0035] The visual inspection device 41 captures images of the printed pattern on the passing substrate 8 at a fixed frequency (e.g., 10 frames per second). The image data is transmitted to the central control unit 1 for real-time processing, and the current ink density of each controlled ink zone i is calculated using image algorithms. ;

[0036] Central control unit 1 sets the ink density of each ink zone With the corresponding target ink density By comparison, density deviation is obtained. ;

[0037] For density deviation For ink areas exceeding the tolerance range, the central control unit 1 generates a corresponding pulse command and sends it to the ink key actuator 42 for that ink area. The actuator drives the ink key 43 to fine-tune its opening (e.g., if...). A negative value indicates shallow ink density, so the ink key opening is increased, thereby changing the ink supply to that area and ultimately bringing the printing density back to the target range. This is a parallel multi-loop control system.

[0038] The registration sensor 51 continuously detects the registration mark lines on the substrate 8 and sends its current position signal. The information is sent to the central control unit 1, which calculates the current location. relative to the reference position offset If the offset If the preset threshold is exceeded, the central control unit 1 immediately sends a command to the registration motor 52 to drive the transmission mechanism of the printing roller 6 to rotate slightly in the circumferential direction, correct the position of the image and text, and eliminate the registration error.

[0039] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model 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, and therefore should not be construed as a limitation of this utility model.

[0040] In this utility model, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," "join," and "fix" 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, 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. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0041] The control method of this utility model is automatic control through a controller. The control circuit of the controller can be implemented by simple programming by those skilled in the art. The power supply is also common knowledge in the field. Since this utility model is mainly used to protect mechanical devices, the control method and circuit connection will not be explained in detail.

[0042] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. An intelligent control system for letterpress printing process, characterized in that, include Central control unit; The human-machine interface is communicatively connected to the central control unit. The intelligent pressure adjustment module is connected to the central control unit. The intelligent pressure adjustment module includes a pressure sensor group for real-time detection of the actual pressure between the printing roller and the impression roller, and a pressure servo driver that receives instructions from the central control unit and drives the pressure adjustment mechanism. The ink supply intelligent control module is connected to the central control unit. The module includes a visual inspection device for online acquisition of printed images and calculation of ink density information, and multiple ink key actuators that receive instructions from the central control unit to adjust the ink key opening. An automatic registration correction module is connected to the central control unit. The module includes a registration sensor for detecting the position of the registration mark line and a registration motor for receiving instructions from the central control unit to adjust the phase of the printing roller. The data management and communication module, integrated with the central control unit, is used to store printing formula data and communicate with external systems.

2. The intelligent control system for letterpress printing process according to claim 1, characterized in that: The pressure sensor group is a thin-film pressure sensor or a piezoelectric force sensor array distributed and installed on the printing roller bearing seat.

3. The intelligent control system for letterpress printing process according to claim 2, characterized in that: The visual inspection device includes a CCD or CMOS industrial camera, a uniform light source that provides illumination for the CCD or CMOS industrial camera, and a computer unit for image processing. The CCD or CMOS industrial camera is mounted above or to the side of the printed material's travel path.

4. The intelligent control system for letterpress printing process according to claim 1, characterized in that: The pressure regulating mechanism is an eccentric sleeve, wedge mechanism, or linear module driven by a servo motor.

5. The intelligent control system for letterpress printing process according to claim 1, characterized in that: The central control unit is a programmable logic controller or an industrial computer.

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