Feedback type ink supply system for letterpress printing machine and ink quantity control method

Abstract

The invention discloses a feedback type ink supply system for a letterpress printing machine. The feedback type ink supply system comprises a rack, a control system, an ink distributing mechanism, an ink fountain mechanism, an ink pouring mechanism and an ink quantity detection mechanism. The ink distributing motor, the ink bar motor and the ink pouring motor are all connected with the control system. One ink distributing roller is made of a metal material to be a metal ink roller, the ink quantity detection mechanism is composed of the metal ink roller and a gray level sensor, the distance between the gray level sensor and the surface of the metal ink roller is 1 cm, and the gray level sensor is connected with a control system. The intensity of reflected light on the metal ink roller is collected at any time through the gray level sensor, the voltage value of the output analog signal is transmitted to the control system, the control system dynamically adjusts the ink supply amount according to the voltage value of the analog signal, and the printing ink amount can be accurately and dynamically controlled.

Description

Technical Field

[0001] The present invention relates to an ink supply mechanism for a relief printing machine, and more particularly to an ink supply structure for feedback-type short-path precise ink supply. Background Art

[0002] In the printing process of a relief printing machine, an ink distributing mechanism is usually used to provide the ink consumption during printing. According to the ink supply method, it is divided into a direct control method and a feedback control method.

[0003] The direct control method is a mechanism in which the ink supply value is set by the ink distributing supply mechanism, and the printing operator sets the ink supply amount according to experience for printing. Since different patterns, different speeds, and different materials of the printed matter result in different ink consumption during the printing process, it is difficult to accurately control the ink supply amount, and the color difference of the printed matter is difficult to meet the production requirements. Specifically, for example, when actually printing a printed matter, 5 milligrams of ink is consumed. Due to factors such as different patterns, different speeds, and different materials of the printed matter, the printing operator cannot obtain the accurate value of 5 milligrams and can only estimate. At the same time, the ink supply system of the printing machine cannot accurately supply 5 milligrams of ink for each printed matter. The double errors result in a small difference between the ink consumption and the supplied ink amount of the printed matter. This excess or insufficient ink amount difference will accumulate in the ink distributing mechanism during the printing process. When the printing operator discovers the color difference of the printed matter, it is actually too late. The printing operator continues to change the ink supply value of the ink supply system of the printing machine and continues this inaccurate process with double errors, resulting in poor printing and color differences.

[0004] Currently, there are also feedback control methods. For example, a method for controlling the ink delivery process of an offset printing press with a control computer and at least one ink delivery device controlled by the control computer is disclosed in a Chinese patent document with publication number CN100999151 and publication date July 18, 2007. The control computer calculates the ink layer thickness required for ink application using spectral reflection values, and implements necessary adjustment processes on the ink delivery device to adjust the calculated ink layer thickness. During the ink adjustment process, the formed printed pattern can be measured inside or outside the printing press. During the printing process, the substrate is measured by a colorimetric device, and the actual ink value thus formed is input into the ink adjustment device. The actual ink value can be compared with a given value, where an adjustment value is formed using a mathematical model, and the adjustment value is input into an ink adjustment element such as an ink metering element in the ink fountain. Using this ink metering element, the ink supply situation can be adapted according to the given ink value. In short, it is to calculate the ink demand based on the print measurement and make adjustments during printing. Another example is that a method and device for controlling the ink of printed matter are disclosed in a Chinese patent document with publication number CN106985512A and publication date July 28, 2017. The method includes: obtaining a preset number of printed samples; wherein, the printed samples are determined according to printing pressure, printing ink type, paper usage amount, and ink application amount; measuring and recording the chromaticity value and density value of the printed samples; establishing a relationship model between the measured chromaticity value and density value, and calculating the optimal density value based on the minimum color difference; according to the optimal density value, determining at least one candidate density value within the density value standard range, and calculating the derivative value of the color difference function corresponding to each candidate density value; according to the calculated derivative value of the color difference function, increasing or decreasing the current ink amount.

[0005] A series of problems existing in the above two feedback control methods are as follows:

[0006] (1) Measurement problems in numerical extraction. Extracting the printed ink amount value requires professional and expensive equipment and mechanisms, such as colorimetric devices, which increases the customer's costs and time. If there are no samples for new customer orders, the values cannot be extracted, and the customer's color requirements cannot be responded to in a timely manner. Moreover, the pattern is generally intermittent, and the ink supply is constant. It is very difficult to measure a constant ink amount with an intermittent pattern during actual operation.

[0007] (2) Problems in adjusting the ink amount during printing. There is an error between the extracted value and the actual ink consumption, and even if it is small, it will accumulate. This causes obstacles during printing.

[0008] (3) Problems of the influence of printing speed change on the ink amount. At different printing speeds, according to Bernoulli's principle, the pressure and thus the ink amount will be different during printing. Frequent and cumbersome measurement of the ink amount value will make the printing process difficult to control.

[0009] (4) Influence of four-color superposition on ink amount value. After four-color overprinting of printed matter, there will be a color phase change, and it will become extremely difficult to extract the numerical value of a single color.

[0010] (5) Influence of materials on ink amount. Different materials have different color phases, and even for the same material, there will be slight differences in color phases for different batches, which will cause inaccurate preset ink amount values.

[0011] (6) Influence of time on the observation of the ink layer of printed matter. As the printed matter changes over time, the color phase of the ink attached to it will change, and it will become very inaccurate to extract the printing ink amount value of the sample provided by the customer.

[0012] (7) Changing the ink supply amount according to the color phase of the printed matter. Because the middle path is relatively long, in modern high-speed printing, when it is often detected that the color phase of the printed matter is incorrect and then adjusted, a lot of materials have often been wasted. Summary of the Invention

[0013] In view of the above-mentioned prior art, the present invention provides a feedback ink supply system and an ink amount control method for a letterpress printing machine, which can realize real-time and accurate control of ink supply.

[0014] To solve the above technical problems, the present invention proposes a feedback ink supply system for a letterpress printing machine, including a frame, a control system, an ink distributing mechanism, an ink fountain mechanism, an ink pouring mechanism, and an ink amount detection mechanism; the ink distributing mechanism includes an ink distributing motor and an ink roller group composed of a plurality of ink distributing rollers, the ink fountain mechanism includes an ink bar motor and an ink bar, and the output end of the ink bar motor is connected to the ink bar; the ink pouring mechanism includes an ink pouring motor and an ink pouring roller, and the output end of the ink pouring motor is connected to the ink pouring roller; the ink distributing motor, the ink bar motor, and the ink pouring motor are all connected to the control system. In the present invention, one of the ink distributing rollers is made of a metal material to form a metal ink roller, the ink amount detection mechanism is composed of the metal ink roller and a grayscale sensor, an installation bracket is provided on the frame, the grayscale sensor is installed on the installation bracket, the distance between the grayscale sensor and the surface of the metal ink roller is 1 cm, and the grayscale sensor is connected to the control system.

[0015] Further, for the feedback ink supply system of the present invention, wherein:

[0016] The material of the metal ink roller is a non-ferrous metal material, preferably stainless steel or surface chromium plating treatment.

[0017] The surface finish of the metal ink roller is above grade 8.

[0018] The power supply voltage of the grayscale sensor is 5V or 10V.

[0019] The ink streaks have the same rotational speed as the ink streak motor; the ink pouring roller has the same rotational speed as the ink pouring motor.

[0020] Meanwhile, the present invention also proposes a method for realizing ink volume control by using the feedback type ink supply system, including the following steps:

[0021] Step 1, determination of the ink volume of the printed matter, including:

[0022] 1-1) Input an initially determined estimated ink volume value into the control system through man-machine dialogue, and the control system determines the rotational speed of the ink streak motor according to the estimated ink volume value;

[0023] 1-2) After the ink layer on the ink roller group of the ink leveling mechanism becomes uniform, take the printed material at this time; observe the color phase of each color ink on the printed material and the ink effect after overprinting, and compare it with the sample provided by the customer; if the color of the printed material is darker or lighter than the color of the sample, reduce or increase the value on the basis of the original estimated ink volume value and input it again; the control system determines the rotational speed of the ink streak motor according to the re-input estimated ink volume value;

[0024] 1-3) According to the adjustment process in the above step 1-2), until the color phase of each color ink on the obtained printed matter and the ink effect after overprinting are consistent with the effect of the sample, the ink volume value at this time is the ink volume value of the printed matter for this printing;

[0025] Step 2, obtaining the standard ink volume value of the printed matter:

[0026] In the state where the ink volume of the printed matter is determined in step 1, the gray-scale sensor outputs a voltage value of an analog signal according to the intensity of the reflected light of the metal ink roller, and the voltage value of the analog signal is displayed on the display screen of the man-machine dialogue of the control system, and this value is stored and recorded as the standard ink volume value of the printed matter for this printing;

[0027] Step 3, dynamic adjustment of the ink volume of the printed matter during printing:

[0028] During printing, the gray-scale sensor transmits the voltage value of the currently output analog signal to the control system 1 at any time, and the currently output voltage value of the analog signal is recorded as the current ink volume value; the control system compares the current ink volume value with the standard ink volume value. If the difference between the current ink volume value and the standard ink volume value exceeds the set threshold, the control system adjusts the rotational speed of the ink streak motor so that the difference between the current ink volume value and the standard ink volume value is within the set threshold range.

[0029] Furthermore, in the ink volume control method of the present invention, the threshold of the difference between the current ink volume value and the standard ink volume value is set to ±0.3V.

[0030] In the above control process, the ink bar motor can be replaced with an ink pouring motor, and the ink bar can be replaced with an ink pouring roller, and the same control effect can be achieved.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] (1) In the printing preparation stage, the operation process is simple and reliable. Monochromatic observation plus overprint direct observation makes it simple and easy for the operator to understand, without the need for the operator to have more experience or additional detection equipment.

[0033] (2) In the printing preparation stage, it can reflect the hues of each color of the printed matter and the overprinted ink in real time, communicate with the customer, and the short ink path realizes precise control of the ink.

[0034] (3) In the printing preparation stage, on-site observation makes the influence of the current printing material on the hue of the ink unobstructed.

[0035] (4) The feedback design during the printing process realizes the moment connection between the consumed ink volume and the supplied ink volume, reducing the working intensity and pressure of the operator.

[0036] (5) The feedback design during the printing process adjusts the ink supply amount according to the ink layer thickness value of the metal ink roller. Often, before the color difference is reflected on the printed matter, the ink supply mechanism has already detected and solved it, greatly improving the yield of the printed matter.

[0037] (6) In actual use, after assigning the standard ink volume value in the printing preparation stage, the machine automatically adjusts the ink supply amount, reducing the operator's training time from several years to several weeks. At the same time, during the printing process, the working intensity and pressure are greatly reduced, and the qualified rate of the printed matter is greatly increased. Description of the Drawings

[0038] Figure 1 is a schematic structural diagram of the ink supply system of the present invention;

[0039] Figure 2 is Figure 1 a schematic diagram of another perspective of the ink supply system shown;

[0040] Figure 3 is a flowchart for determining the ink volume and standard ink volume value of the printed matter in the method of the present invention;

[0041] Figure 4 is a flowchart for dynamically adjusting the ink volume of the printed matter during the printing process in the method of the present invention.

[0042] In the figure:

[0043] 1 - control system 2 - control cable 3 - ink bar 4 - ink bar motor

[0044] 5 - Ink - pouring motor 6 - Ink - leveling motor 7 - Ink - leveling mechanism 8 - Metal ink roller

[0045] 9 - Grayscale sensor 10 - Ink - pouring roller 11 - Ink fountain mechanism 12 - Ink - pouring mechanism Detailed implementation manners

[0046] A feedback - type ink volume control method for a letterpress printing machine proposed by the present invention has a design concept as follows: By using the working principle of a grayscale sensor, the material of one of the ink - leveling rollers (or its surface) in the ink supply device of the printing machine is changed to a metal material. The grayscale sensor is used to collect the intensity of the reflected light on the metal ink roller at any time, and the voltage value of the analog signal output is transmitted to the control system. The control system dynamically adjusts the size of the ink supply according to the voltage value of the analog signal. The structure of the feedback - type ink supply system of the present invention mainly includes a frame, a control system 1, an ink - leveling mechanism 7, an ink fountain mechanism 11, an ink - pouring mechanism 5, and an ink volume detection mechanism. The ink - leveling motor 6, the ink bar motor 4, and the ink - pouring motor 5 are all connected to the control system 1. In the present invention, one of the ink - leveling rollers is made of a metal material to form a metal ink roller 8. The ink volume detection mechanism is composed of the metal ink roller 8 and a grayscale sensor 9. The distance between the grayscale sensor 9 and the surface of the metal ink roller 8 is 1 cm, and the grayscale sensor 9 is connected to the control system 1. The intensity of the reflected light on the metal ink roller 8 collected by the grayscale sensor 9 at any time is used, and the voltage value of the analog signal output is transmitted to the control system 1. The control system 1 dynamically adjusts the size of the ink supply according to the voltage value of the analog signal, so as to achieve precise and dynamic control of the ink volume for printing.

[0047] The following further describes the present invention in conjunction with the accompanying drawings and specific embodiments, but the following embodiments are by no means any limitation to the present invention.

[0048] The present invention provides a feedback - type ink supply system for a letterpress printing machine, as Figure 1 and Figure 2 shown, which includes a frame, a control system 1, an ink - leveling mechanism 7, an ink fountain mechanism 11, an ink - pouring mechanism 12, and an ink volume detection mechanism. The ink - leveling mechanism 7 includes an ink - leveling motor 6 and an ink roller group composed of multiple ink - leveling rollers. The ink - leveling motor 6 drives the rotation of the ink roller group composed of multiple ink - leveling rollers to achieve the uniformity and transfer of ink. The ink - leveling motor 6 is electrically connected to the control system 1. The ink fountain mechanism 11 includes an ink bar motor 4 and an ink bar 3. The output end of the ink bar motor 4 is mechanically connected to the ink bar 3. The ink bar 3 has the same rotation speed as the ink bar motor 4. The ink bar motor 4 is electrically connected to the control system 1. The control system 1 determines the start - stop and speed of the ink bar motor 4, thereby determining the size of the ink output by the ink fountain mechanism 11; this structure is well - known in the industry.

[0049] The ink pouring mechanism 12 includes an ink pouring motor 5 and an ink pouring roller 10. The output end of the ink pouring motor 5 in the ink pouring mechanism 11 is mechanically connected to the ink pouring roller 10. The ink pouring roller 10 rotates at the same speed as the ink pouring motor 5. The ink pouring motor 5 is electrically connected to the control system 1. The control system 1 determines its start / stop and speed, thereby determining the swing frequency of the ink pouring roller 10. The swing frequency of the ink pouring roller 10 determines the speed of the ink volume transferred from the ink fountain mechanism 11 to the ink distributing mechanism 7. This structure is well-known in the industry.

[0050] In the present invention, one of the ink distributing rollers is made of a metal material to form a metal ink roller 8, which has a metallic luster on its surface and can provide the luster state after the surface of the metal ink roller 8 is covered with ink. The ink volume detection mechanism is composed of the metal ink roller 8 and a grayscale sensor 9. An installation bracket is provided on the frame, and the grayscale sensor 9 is installed on this installation bracket. In this embodiment, the metal ink roller 8 is a chrome-plated metal roller with a surface finish of grade 8. The power supply voltage of the grayscale sensor 9 is 10V. The distance between the grayscale sensor 9 and the surface of the metal ink roller 8 is 1 cm. The grayscale sensor 9 is connected to the control system 1. The grayscale sensor 9 outputs an analog signal of 0V - 10V (power supply voltage) by detecting the intensity of the reflected light on the surface of the metal ink roller 8 after the surface of the metal ink roller 8 is covered with ink, realizes the real-time detection of the ink layer thickness, and transmits this data to the control system 1.

[0051] In this embodiment, the ink distributing motor 6, the ink bar motor 4, the ink pouring motor 5, and the grayscale sensor 9 are respectively connected to the control system 1 through control cables 2. A control program is set in the control system 1, which is responsible for receiving the signal of the grayscale sensor 9 and feedback controlling the start / stop and speed of the motors.

[0052] In this embodiment, the ink roller group of the ink distributing mechanism 7 is driven by the ink distributing motor 6 under the control of the control system 1 to realize the ink distribution function; the ink bar motor 4 controlled by the control system 1 drives the ink bar 3 to rotate, evenly lifts the ink in the ink fountain, and supplies the ink to the ink pouring roller 10 when it swings and contacts the ink pouring roller 10 for transmission to the ink distributing mechanism 7; the ink pouring motor 5 controlled by the control system 1 swings left and right to drive the ink pouring roller 10 to contact the ink bar 3 in the ink fountain mechanism 11 and the ink distributing mechanism 7, and reciprocally swings to bring the ink in the ink fountain mechanism 11 into the ink distributing mechanism 7. This ink pouring mechanism is a well-known technology. The control system 1 controls the ink transfer amount of the ink pouring mechanism and the control system 1 controls the ink fountain mechanism to have the same function and effect.

[0053] In the present invention, the metal ink roller 8 rotates together with the ink distribution mechanism. The metal ink roller 8 has a metallic luster. When used in cooperation with the grayscale sensor 9, it can well detect the strength of the metallic luster after the ink covers the surface of the metal ink roller 8. The grayscale sensor 9 can obtain different grayscale values according to the strength of the metallic luster, thereby obtaining the ink coverage thickness, i.e., the ink amount value. The result has been accurately verified in practice.

[0054] The process of realizing the adjustment of the ink supply amount by the ink supply system for the feedback type short-path ink in the letterpress printing machine of the present invention is as follows Figure 3 and Figure 4 shown, including the following steps:

[0055] Step 1, determination of the ink amount of the printed matter: As Figure 3 shown, the operator observes the color depth of the printed product to be printed or refers to the estimated ink amount value of the previously printed printed matter, and inputs the estimated ink amount value 100 through the touch screen in the control system. In this embodiment, the control system calculates according to the value of the estimated ink amount value / 5, and uses revolutions per minute as the rotation speed of the ink bar motor 4 in the ink fountain mechanism 11, that is, 20 revolutions per minute. The ink bar 3 connected to the output shaft of the ink bar motor 4 supplies ink to the ink distribution mechanism 7 at a rotation speed of 20 revolutions per minute. After the ink layer in the ink distribution mechanism 7 is uniform, take the material that has been printed at this time. The operator observes the hue of each color ink on the printed matter and the ink effect after overprinting, and compares it with the sample provided by the customer.

[0056] If the color of the printed matter is darker than that of the sample, reduce the value on the basis of the original estimated ink amount value and re-enter it. For example, reduce the estimated ink amount value from the original 100 to 90; the control system controls the rotation speed of the ink bar motor 4 in the ink fountain mechanism 11 to be 90 / 5 = 18 revolutions per minute. At this rotation speed, the ink supply amount transferred from the ink fountain mechanism 11 to the ink distribution mechanism 7 is reduced by 10%; similarly, if the color of the printed matter is lighter than that of the sample, increase the value on the basis of the original estimated ink amount value and re-enter it to increase the ink supply amount transferred from the ink fountain mechanism 11 to the ink distribution mechanism 7.

[0057] According to the above adjustment process, until the hue of each color ink on the obtained printed matter and the ink effect after overprinting are consistent with those of the sample.

[0058] Step 2, obtaining the standard ink amount value of the printed matter; As Figure 3As shown, when the operator obtains the most satisfactory printing effect, an instruction is issued through the control system 1. The gray-scale sensor 9 detects the intensity of the metallic luster on the surface of the metal ink roller 8. In the present invention, the voltage value range of the analog signal output by the gray-scale sensor 9 is 0 - 10V, and the voltage value of this analog signal changes with the intensity of the metallic luster on the surface of the metal ink roller 8 after being covered by the printing ink. At this time, the intensity of the metallic luster on the surface of the metal ink roller 8 detected by the gray-scale sensor 9 is displayed as the voltage value of the analog signal on the screen of the input device (such as a touch screen). For example, when the hue of each color ink on the printed product and the ink effect after overprinting are consistent with those of the sample, the voltage value of the analog signal displayed on the screen is 5V. In the present invention, the voltage value of the analog signal at this time is defined as the standard ink amount value of the printed product of this batch of printing.

[0059] Step Three, dynamic adjustment of the ink amount during printing: As Figure 4 shown, during the printing process of this batch of printed products, the gray-scale sensor 9 will detect the intensity of the metallic luster on the surface of the metal ink roller 8 after being covered by the printing ink, and transmit the voltage value of the currently output analog signal to the control system 1 at any time. When the ink layer is thick, the metallic luster on the surface of the metal ink roller 8 after being covered by the printing ink is weak, and the corresponding voltage value of the analog signal is low. On the contrary, when the ink layer is thin, the corresponding voltage value of the analog signal is high. In the present invention, the currently obtained voltage value of the analog signal is defined as the current ink amount value. During the printing process, the control system 1 will compare the currently obtained current ink amount value with the standard ink amount value obtained in Step 2 at any time. If the difference between the current ink amount value and the standard ink amount value exceeds ±0.3, the control system 1 controls the rotation speed of the ink bar motor 4 in the ink fountain mechanism 11 according to the comparison result, thereby determining the rotation speed of the ink bar 3 connected thereto. For example, if the current ink amount value is 4.6V (that is, the difference between the current ink amount value and the standard ink amount value exceeds -0.3), the control system slows down the rotation speed of the ink bar motor 4 in the ink fountain mechanism, thereby determining the rotation speed of the ink bar 3 connected thereto, so as to reduce the ink output to the ink distribution mechanism 7, making the ink layer on the surface of the metal ink roller 8 rotating together with the ink distribution mechanism 7 thinner, making the metallic luster on the surface of the metal ink roller 8 stronger, and making the current ink amount value rise to 4.7V. If the current ink amount value is 5.4V, which is obviously larger than the standard ink amount value and exceeds the set threshold of +0.3, the rotation speed of the ink bar motor 4 in the ink fountain mechanism is increased, thereby determining the rotation speed of the ink bar 3 connected thereto, so as to increase the ink output to the ink distribution mechanism 7, making the ink layer on the surface of the metal ink roller 8 rotating together with the ink distribution mechanism 7 thicker, making the metallic luster on the surface of the metal ink roller 8 weaker, and making the current ink amount value drop to 5.3V. The normal operation process is to make the current ink amount value and the standard ink amount value fluctuate within the range of ±0.3 according to the above control, so that the current ink amount value dynamically and continuously approaches the standard ink amount value to ensure a satisfactory printing effect.

[0060] In the control method of the present invention, the rotational speed of the ink bar motor 4 in the control is replaced with the rotational speed of the ink pouring motor 5, and the ink bar 3 is replaced with the ink pouring roller 10, and the effects are the same.

[0061] Although the present invention has been described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative rather than restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many improvements and changes without departing from the purpose of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A feedback ink supply system for a letterpress printing machine, comprising a frame, a control system (1), an ink distribution mechanism (7), an ink fountain mechanism (11) and an ink pouring mechanism (12); the ink distribution mechanism (7) includes an ink distribution motor (6) and an ink roller group composed of a plurality of ink distribution rollers, the ink fountain mechanism (11) includes an ink bar motor (4) and an ink bar (3), and the output end of the ink bar motor (4) is connected to the ink bar (3); the ink pouring mechanism (12) includes an ink pouring motor (5) and an ink pouring roller (10), and the output end of the ink pouring motor (5) is connected to the ink pouring roller (10); the ink distribution motor (6), the ink bar motor (4) and the ink pouring motor (5) are all connected to the control system (1); characterized in that, One of the ink distribution rollers is made of a metal material to form a metal ink roller (8), and the feedback ink supply system further includes an ink quantity detection mechanism, which is composed of the metal ink roller (8) and a gray scale sensor. An installation bracket is provided on the frame, and the gray scale sensor (9) is installed on the installation bracket. The distance between the gray scale sensor (9) and the surface of the metal ink roller (8) is 1 cm, and the gray scale sensor (9) is connected to the control system (1).

2. The feedback ink supply system according to claim 1, wherein The material of the metal ink roller (8) is a non-ferrous metal material.

3. The feedback ink supply system according to claim 1, wherein The material of the metal ink roller (8) is stainless steel.

4. The feedback ink supply system according to claim 1, wherein The surface finish of the metal ink roller (8) is above grade 8.

5. The feedback ink supply system according to claim 1, wherein The power supply voltage of the gray scale sensor (9) is 5V or 10V.

6. The feedback ink supply system according to claim 1, wherein The ink bar (3) has the same rotation speed as the ink bar motor (4); the ink pouring roller (10) has the same rotation speed as the ink pouring motor (5).

7. A method for controlling the ink supply amount of a feedback ink supply system for a letterpress printing machine, characterized in that, Adopt the feedback ink supply system as described in any one of claims 1-6, and include the following steps: Step 1, determination of the ink quantity of the printed matter, including: 1-1) Input an initially estimated ink quantity value into the control system (1) through man-machine dialogue, and the control system (1) determines the rotation speed of the ink bar motor (4) according to the estimated ink quantity value; 1-2) After the ink layer on the ink roller group of the ink distribution mechanism (7) is uniform, take the printed material at this time; observe the color of each color ink on the printed material and the ink effect after overprinting and compare it with the sample provided by the customer; if the color of the printed material is darker or lighter than the color of the sample, then reduce or increase the value on the basis of the original estimated ink quantity value and input it again; the control system (1) determines the rotation speed of the ink bar motor (4) according to the re-input estimated ink quantity value; 1-3) According to the adjustment process in the above step 1-2), until the color of each color ink on the obtained printed matter and the ink effect after overprinting are consistent with the effect of the sample; Step 2, obtaining the standard ink quantity value of the printed matter: In the state where the ink quantity of the printed matter is determined in Step 1, the gray scale sensor (9) outputs a voltage value of an analog signal according to the intensity of the reflected light of the metal ink roller (8) detected, and the voltage value of the analog signal is displayed on the display screen of the man-machine dialogue of the control system (1), and this value is stored and recorded as the standard ink quantity value of the printed matter for this printing; Step 3, dynamic adjustment of the ink quantity of the printed matter during the printing process: During the printing process, the gray-scale sensor (9) transmits the voltage value of the currently output analog signal to the control system (1) at any time, and the voltage value of the currently output analog signal is denoted as the current ink amount value; the control system (1) compares the current ink amount value with the standard ink amount value. If the difference between the current ink amount value and the standard ink amount value exceeds the set threshold, the control system (1) adjusts the rotation speed of the ink bar motor (4), so that the difference between the current ink amount value and the standard ink amount value is within the set threshold range.

8. The ink volume control method according to claim 7, characterized in that, Set the threshold for the difference between the current ink amount value and the standard ink amount value to ±0.3V.

9. The ink amount control method according to claim 7, wherein Replace the ink bar motor (4) therein with an ink pouring motor (5), and replace the ink bar (3) therein with an ink pouring roller (10).

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