The structure and working process of the roller printing machine
Roller printing uses a copper roller with a gravure (negative pattern) or relief (positive pattern) pattern engraved on the surface for printing. Therefore, the roller printing machine is also called the copper roller printing machine. The engraved copper roller is referred to as the printing roller. The positive pattern is mainly used for top printing, and the negative pattern is mainly used for printing cotton, polyester/cotton and chemical fiber fabrics. According to the arrangement of copper rollers, it can be divided into three types: radial type, standing type and inclined type; according to the number of printing colors, it can be divided into four colors, six colors, eight colors and ten colors; according to only one side of the fabric or on both sides at the same time Printing can be divided into single-sided printing machines and double-sided printing machines. Among them, the eight-color radiation single-sided roller printing machine is commonly used.
1. Equipment structure and working process
The roller printing machine must form a printing combined machine with other unit machines and general devices, as shown in Figure 8-1. It mainly consists of cloth in and out devices, printing head, hot air pre-drying machine, drum drying machine, transmission device, etc.
11 Fabric feeding device
The fabric feeding device of the roller printing machine is divided into interlining cloth feeding and white cloth feeding Cloth feeding device. The interlining cloth is fed in the tight type, while the white cloth is mostly fed in the loose type. It is fed in the form of overfeeding, so that the fabric hangs in the shape of a cloth ring. When the power is used, the speed of the cloth feeding overfeeding roller is controlled to ensure that the white cloth is in a relaxed state. Enter the front of the machine to make the fabric tension consistent and achieve excellent printing effects. The liningless printing machine only has a white cloth feeding device.
21 Printing head
The printing head is the core part of the roller printing combined machine. It mainly consists of a frame, a flower tube, a pressure roller (also called a pressure roller), a pressurizing mechanism, a pulp feeding device, a pattern device and Transmission device and other components, as shown in Figure 8-2. It is customary to call the side where the cloth enters the feeding point the rear vehicle, and the side where the cloth comes out is called the front vehicle.
(1) Rack: The rack, commonly known as wall panel, is used to carry the weight of pressure rollers, flower tubes, flower tube pressurizing mechanisms, slurry feeding devices, etc. It is cast from gray cast iron, with one piece on each side. The lower part is mounted on two horizontal base plates. The upper part is connected by a cross beam as a support. It is hollow and radial, with two pairs of press roller bearing seats and multiple pairs of flower tubes evenly arranged. Bearing box. The center slideway is the pressure roller bearing seat.
(2) Pressure roller: The pressure roller is a hollow roller made of cast iron. It is installed on the pressure roller bearing seat. Turning the screw rod can make the pressure roller move up and down. The core of the pressure-bearing roller is long, and both ends of the shaft head extend out of the frame. One end is equipped with a broach device, and the other end is looped around a central gear of the flower tube. This gear meshes with the gears on each flower tube to drive each flower tube. , the pressure-bearing roller is driven by the friction of the flower tubes, thus avoiding the accumulation of circumferential errors between the flower tubes.
The diameter of the pressure roller is generally 750~1350mm, which is determined by color registration. The more colors there are, the larger the diameter is. For example, the diameter of the pressure roller of a four-color printing machine is 750mm, while the diameter of the pressure roller of an eight-color printing machine is 1050mm. The diameter of the pressure-bearing roller is generally small, because the smaller the diameter, the greater the pressure per unit area under the same pressure, which is conducive to printing fine patterns. In addition, the diameter is small, the volume and weight are also small, which is convenient for installation and debugging.
The surface of the pressure roller should have a certain degree of elasticity so that the pattern can be printed clearly. For this reason, some cast iron rollers are covered with 12 to 22 layers of wool lining cloth with hemp warp and weft, which is called wool lining cloth pressure-bearing roller. Some cast a uniform layer of rubber on the surface of the cast iron roller, which is called rubber pressure-bearing roller.
When using the wool interlining pressure roller printing, the wool interlining should be covered with a layer of jointless annular rubber interlining with a clean surface, uniform thickness and hardness to assist the elasticity of the wool interlining, protect the wool interlining, and cover the roughness of the wool interlining Surface and joint prints. In order to prevent the printing paste from penetrating and contaminating the rubber interlining, a cotton or polyester interlining slightly wider than the flower tube is placed between the rubber interlining and the printed fabric, which is called printed interlining. It is customary to call wool interlining, rubber interlining and printed interlining the “three cloths”.
In order to save industrial fabrics and reduce consumption, except for the 1600 printing machine, most of them now use rubber pressure rollers instead of “three cloths” printing, that is, printing without interlining. The rubber layer of the rubber pressure roller is 10~15mm thick and the hardness is HSA94~96. The rubber surface is required to be flat, pressure resistant and chemical corrosion resistant. The rubber pressure-bearing roller is easily stained by the penetrating color paste. If you use a rubber pressure-bearing roller for direct printing, you must use the color paste removal device as shown in Figure 8-3 to remove the color paste remaining on the surface of the pressure-bearing roller to avoid contamination. Printed fabric. It is not suitable for printing patterns with many color registrations and large-area patterns and thin fabrics.
(3) Flower tube: The flower tube is made of copper-zinc alloy (containing 97.5% to 98% copper and 2% to 2.5% zinc) The hollow cylinder is cast by centrifugal method and installed on the flower tube bearing seat.
The structure of the flower tube is shown in Figure 8-4. The inner hole of the flower tube is a tapered hole with a taper of 1:288, which matches the corresponding taper of the flower tube shaft. There is a convex long key in the inner hole of the flower tube and a concave keyway on the shaft. The two are closely matched to ensure relative stability. The fascia shaft is made of 45 steel.
When installing a flower tube, a piece of paper is often placed between the inner hole of the flower tube and the outer circle of the shaft, and then the flower tube disassembler is used to apply horizontal pressure to press the shaft into the tube to fix it.
The circumference of the new flower tube is 440~450mm. The flower tube can be reused. When carving a new pattern, the old pattern on the tube surface can be turned away and a new pattern can be carved after grinding. When the circumference of the flower tube is less than 350mm, it cannot be used.�Use. The circumferences of each flower tube of each set of patterns must be equal, with an acceptable error of ±0.1mm. After the flower tube is engraved, the surface of the tube must be chromium-plated to improve its hardness and cleanliness, increase its wear resistance and corrosion resistance, extend its service life, and prevent printing defects caused by incomplete tube surfaces. Usually, the flower tubes are numbered in sequence according to the forward direction of the fabric, with the feeding point being 1#, and so on.
(4) Fountain pressurizing mechanism: The pressurizing mechanism exerts pressure on the cone through the bearings at both ends of the cone shaft. In order to make the printed pattern clear and the left and right printing pastes uniform, the amount of pressure must be appropriate. If the pressure is too light, the printed pattern will be light in color or even exposed. If the pressure is too heavy, it will be blurred and distorted, and it will also increase power loss and worsen the situation. Parts are worn. Generally, the flower tubes with thick lines and large patterns and the pressure roller used as the finishing plate should be pressed lightly, and the flower tubes with thin lines, moire and snowflakes should be pressed hard. The linear pressure range is 100~600N/cm, and 200~400N/cm is commonly used. Depending on the length of the flower tube, the total pressure of each flower tube can reach 2×104~8×104N. In addition, the pressurizing mechanism should also meet the following process and operating requirements:
① It can not only centrally control the advancement and retreat of the flower tube and bearing seat, but also accurately adjust the pressure on the left and right sides respectively.
② The pressurizing system should be elastic. When the cloth joint passes through the pressure point or the shaft is bent, it can act as a buffer and reduce pressure fluctuations.
There are many ways to pressurize the flower tube, including screw rod pressurization, weight lever pressurization, air pressure pressurization and hydraulic pressurization, etc.
a. Screw pressurization: The first and last two flower tubes of old-fashioned printing machines are commonly used for pressurization with screw rods. The structure is shown in Figure 8-5. Since the sleeve nut is positioned on the frame with a feather key and cannot rotate, when the screw rod is rotated for pressure, the surface of the tube and the surface of the pressure roller are pressed against each other. When the pressure gradually increases, the nut retreats due to the reaction force, causing the spring behind the nut to be compressed, thereby using the elastic force of the spring to pressurize the flower tube through the sleeve nut and the adjusting screw. The spring can play a buffering role during printing. The size of the pressure is determined by the compression force of the spring. When releasing the pressure from the flower tube, just reverse the screw rod.
b. Heavy hammer lever pressurization: Except for the first and last two flower tubes of the old-fashioned printing machine, the rest of the flower tubes are pressurized by a heavy hammer lever, as shown in Figure 8-6. It applies pressure through a set of compound levers and uses the weight of a heavy hammer. The principle of adding and releasing pressure is the same as that of the spring pressurizing mechanism, and it still relies on the spring to play a buffering role.
The above two pressure mechanisms have simple structures and are easy to manufacture and maintain. The springs can act as a buffer, but they are manually operated and there is no pressure indication. , and after using it for a certain period of time, the working state is not stable enough, so fluid pressurization is currently used instead. In this way, it not only improves the degree of mechanization and reduces labor intensity, but also the pressure on both sides of each tube can be centrally indicated through the pressure gauge, creating good conditions for improving printing quality.
c. Gas pressurization mechanism: Figure 8-7 shows a membrane air chamber type air pressure pressurization device. It is realized by using compressed air to directly act on the air film, amplifying the pressure through a first-level lever, and pressing the screw rod on the flower tube bearing. This mechanism has a simple structure, but it still needs to turn the screw rod to adjust the pressure of the flower tube, so it is rarely used.
d. Hydraulic pressurizing mechanism: Figure 8-8 shows the flower tube hydraulic pressurizing system. The medium-pressure pressure oil output from the vane pump enters the large accumulator tank through the pressure reducing valve and one-way valve. When the reversing valve is in the pressurized position, the pressure oil enters the oil passage to each flower tube pressurizing cylinder through the PA channel. When printing, open the stop valve, and the pressure oil will enter the small accumulator and chamber C of the oil cylinder, causing the flower tube to press against the pressure-bearing roller. When the pressure reaches the required value, close the stop valve, and the work of the oil cylinder will not be affected by other oil circuits. And the voltage is stabilized by the action of the small accumulator. When relieving pressure, first open the stop valve, and then turn the reversing valve to the pressure relieving position, then the pressure oil in the oil cylinder will flow back into the oil tank, and the piston rod of the oil cylinder will pull the flower tube away from the pressure roller.
e. Gas-liquid combined pressurization mechanism: The M172 eight-color printing machine adopts a gas-liquid combined pressurization system. The pressurization principle is shown in Figure 8-9. When pressurizing, 600-700kPa compressed air passes through the pressure reducing valve and main valve, enters the rotary valve to apply pressure to the oil in the air and oil pressure converter, and the pressurized oil is transported to each flower tube through the manual reversing valve. When , the rotary valve is in the pressurizing position, oil circuits a and b are connected, and pressurization is completed. When the manual reversing valve is in the low-pressure position, PA is connected, and the pressure oil enters the D chamber of the oil cylinder through the ring valve to pressurize the flower tube; when the reversing valve is in the high-pressure position, PB is connected, and the pressure oil enters the lower part of the supercharger. , after supercharging, it is output from the upper part, enters the D chamber of the oil cylinder through the OA oil line of the reversing valve and the ring valve, and pressurizes the flower tube. When the left and right pressure of the flower tube reaches the required value, close the ring valve to stabilize the pressurized oil circuit. When relieving pressure, turn the rotary valve to the pressure relieving position. At this time, a and c, b and d are connected respectively. The compressed air will push the oil pressure in the air-oil pressure converter into the C chamber of the auxiliary cylinder and pass through the OA oil circuit. Lower the piston of the supercharger to reset, then open the ring valve, and place the manual reversing valve in the low-pressure position. The oil in the air-oil pressure converter enters the E chamber of the oil cylinder, and the oil in the D chamber returns to the air-oil pressure converter. , the oil pressure drops to zero, and the flower tube is relieved of pressure.
(5) Slurry feeding device: The slurry feeding device consists of a pulp plate, a pulp feeding roller, a pulp blade and a yarn removal scraper, as shown in Figure 8-10. Each flower tube is equipped with a slurry feeding device.
The pulp disc is made of thin copper plate or stainless steel plate, can be loaded and unloaded on the frame, and its position can be adjusted by adjusting bolts. The color paste can be sent from the pulp barrel to the pulp tray by a gear pump or a pneumatic piston pump, andThe small liquid level controller on the pulp tray automatically controls the pulp delivery volume.
The pulp feed roller is driven by the gear at the shaft end of the tube or by friction on the tube surface. When the paste roller rotates, it transfers the color paste to the flower tube, and then uses the scraper that moves back and forth to scrape off the excess color paste on the surface of the flower tube, so that the color paste is hidden in the oblique lines of the flower tube’s shadow pattern, and is printed on the fabric to form a pattern. . There are several types of pulp feeding rollers, including bristle rollers, brown hair rollers, rubber rollers and nylon rollers. Because neither the pig bristle roller nor the brown hair roller can adapt to both alkaline and acidic colorants, they are difficult to clean and prone to lint, and the rubber roller cannot effectively remove yarn ends, pulp blocks and other solids embedded in the twill lines of the flower tube. Impurities, therefore, nylon rollers are commonly used.
Squeegee blades are made of high carbon steel or stainless steel, namely blue steel knives and white steel knives. Blue steel knives are brittle, while white steel knives are tough and resistant to chemical corrosion. In order to increase the rigidity of the squeegee blade, a liner blade is installed on the back of it. The thickness of the blade is often expressed by the “gap” number. The higher the number, the thinner the blade. Commonly used scraper numbers are 18#～26#, and commonly used copper knife numbers are 24#～26# . The length of the scraper should be 30~35mm longer than the flower tube. In order to protect the pattern of the floral tube and the scraper and give full play to the effectiveness of the scraper, the scraper is driven by the broach device during printing and reciprocates along the axis of the floral tube. Originally, the broaching device was driven by a pressure-bearing roller, and the frequency of reciprocation of the squeegee changed with the speed of the vehicle, which had a negative impact on the squeegee effect. Now, they have all been driven by separate electric motors.
The yarn removal scraper, commonly called a knife, is made of brass or phosphor bronze, so it is also called a copper knife. It is installed in front of the flower tube in the direction of reversal, opposite to the scraper knife, and is also called a copper knife. The yarn removal scraper is generally fixed and pressurized by a spiral tension spring or a heavy hammer. It has two functions: one is to scrape off impurities such as yarn ends and fluff attached to the floral tube, and the other is to scrape off the residual slurry adhering to the surface of the floral tube to avoid printing defects on the intarsia tube and reduce color transfer.
(6) Flower alignment device: When printing in multiple colors, the corresponding parts of each flower tube pattern must maintain precise relative positions according to standard pattern requirements. Therefore, the printing machine must have a pattern setting mechanism with high adjustment accuracy, simple structure, reliable performance, easy and sensitive operation.
The adjustment form of the flower tube is shown in Figure 8-11, including pressure adjustment, horizontal adjustment, transverse adjustment and front and rear (according to the warp direction of the fabric) direction adjustment, etc. The last three forms of adjustment determine the spatial position of the flower tube, which directly affects the flower alignment accuracy.
① Pressure adjustment: Pressure adjustment is by adjusting the screw rod, weight or pressure regulating valve in the flower tube pressure mechanism on the outside of the flower tube bearing. Adjust the pressure at both ends of the flower tube so that the line pressure on the left, middle and right sides of the flower tube is consistent. Or adjust the pressure of the front and rear flower tubes so that the fabric has appropriate tension between the flower tubes.
② Horizontal adjustment and lateral adjustment: Horizontal adjustment and lateral adjustment are achieved by rotating the horizontal adjustment screw and lateral adjustment screw of the flower tube bearing box. The structure of the flower tube bearing box is shown in Figure 8-12. The bearing box is installed on the radial parts of the left and right frames and serves as the support for the fayette shaft.
Horizontal adjustment is to adjust the height position of both ends of the flower tube so that the flower tube is level, commonly known as up-and-down flower arrangement. It rotates the horizontal adjustment screw of the flower tube bearing seat to move the bearing bush (or rolling bearing sleeve) up and down, allowing the horizontal fine adjustment of the flower tube to complete the alignment, as shown in Figure 8-13(a).
Lateral adjustment is to adjust the axial position of the flower tube, also called lateral alignment or weft adjustment. It is done by adjusting the lateral adjustment screw in the bearing box at the left or right end of the flower tube to push the copper bearing bush to move left and right, so that the horizontal fine adjustment of the flower tube is completed. For flowers, see Figure 8-13(a). Another improved transverse alignment device only needs to be operated at one end, and its structure is shown in Figure 8-13(b). The bump on the cylindrical bearing seat of the fascia shaft is embedded in the block 3 of the supporting plate. The supporting plate is connected with a non-rotatable screw rod. The adjusting nut on the screw rod can only rotate but cannot move along the axial direction of the screw rod 6. Turning the nut causes the screw to move axially, so that the supporting plate passes through the squares and bumps, driving the bearing to move laterally, so that the flower tube can be adjusted laterally to achieve horizontal alignment.
③ Front-to-back direction adjustment: Front-to-back direction adjustment is to adjust the lead or lag in the circumferential direction of the flower tube, which is also called front-to-back alignment or circumferential alignment. The adjustment of the front and rear direction of the fascia is actually achieved by rotating the angle of the fascia, and this angle adjustment is accomplished by the change of the rotation speed of the fascia, which is a dynamic adjustment. Common adjustment mechanisms include electromagnetic flower setting devices, electric flower setting devices and pneumatic flower setting devices.
a1 Electromagnetic flower setting device: As shown in Figure 8-14, gear 1 that directly meshes with gear 9 is looped around gear 1′ On the sleeve axle, a bridge wheel 8 is installed between gears 1′ and 9, and gear 9 and worm 4 are coaxial.
During normal operation, electromagnet A and electromagnet B are not energized, and the rotational speeds of the gears on the main shaft 10 are equal. When you need to align flowers, press the button, electromagnet A or electromagnet B is energized, and attracts friction plate a or friction plate b, causing gear 1 or 1′ to stop, and gear 9 to rotate or reverse, through the epicyclic gear train, so that Gear 3 and flower tube gear 14 obtain an additional rotation speed (increase or decrease), thereby causing relative displacement between the flower tube and the fabric, achieving the purpose of facing the flowers front and back. Displacement size and button time�� is directly proportional to the short one.
The electromagnetic flower alignment device is safe and convenient to operate and can continuously align flowers. However, the structure is complex and the performance is not stable enough. It is currently rarely used.
b1 Electric flower setting device: Also called electric differential flower setting device, it is a commonly used flower setting method at present. It can perform front and rear flower setting and horizontal flower setting respectively, as shown in Figure 8-15.
Circumferential alignment: spur gear 2 and worm gear 7 driven by the central large gear are looped on the main shaft 11, spur gear 2 and bevel gear 3 are connected as one, worm gear 7 and bevel gear 5 are connected as one, and the cone Gear 3 and bevel gear 5 have the same number of teeth. The bevel gear 4 and the bevel gear 6 have the same number of teeth and are looped on the cross short shaft 12. The cross short shaft (or rotating arm) is connected to the main shaft 11 to form an epicyclic gear train. The bevel gear 5 is driven by a 0.25kW, 1400r/min three-phase asynchronous motor through a two-stage worm gear pair.
Horizontal alignment: Since the right end of the universal coupling is embedded in the left end of the spindle, it can rotate with the spindle and along the axis of the spindle. Move slightly left and right. During normal operation, the three-phase asynchronous motor does not rotate. When horizontal alignment is required, press the relevant button, and the three-phase asynchronous motor 17 will rotate forward or reverse, decelerate through the secondary worm gear and worm reducer, drive the external thread shell, and drive the universal coupling to drive the flower tube slightly along the axial direction. Move left and right to achieve horizontal alignment.
The electric alignment device can perform circumferential and transverse alignment continuously, with centralized button control, making the operation safe and convenient, but the structure is complex and it occupies a large area.
c1 Pneumatic alignment device: Figure 8-16 shows the schematic diagram of the pneumatic alignment device of the M172 printing machine. Gears 1, 2, 3 and the rotating arm H form an epicyclic gear train, and gears 4′, 5′ and 4, 5 each form a pair of coaxial gears with different axes. During normal operation, the film air chambers 6′ and 6 are not supplied with compressed air, and the gears 4′, 4 and 5′, 5 are respectively driven by the gear 3′ on the main shaft and the gear Z H on the rotating arm H to rotate at a certain speed. turn around. The epicyclic gear train does not work. Gears 1 and 3 and the rotating arm H rotate around the OO’ axis in the same direction and at the same speed. Gear 2 revolves around the OO’ axis but does not rotate. When circumferential alignment is required, press the air valve to allow compressed air to flow into the air film chamber 6′ or 6, push gear 4′ or 4 to the left, and the end teeth of gears 4′ and 5′ or 4 and 5 mesh. Gear 5′ or 5 rotates at a speed of 4′ or 4. The rotating arm H is provided with an additional rotational speed through the rotating arm gear ZH, and the main shaft OO’ is provided with an additional rotating speed through the epicyclic gear train, thereby achieving circumferential alignment. You can also turn the manual gear 7 when parking, adjust the circumferential position of the flower tube, and perform manual flower alignment.
After the registration is completed, the compressed air in the air chamber is discharged, the clutch is disengaged, and the flower tube can be printed at normal operating speed. An elastic brake pin is installed at K in the figure to prevent inertial escape.
The pneumatic alignment device has a simpler structure and is more convenient to manufacture. The alignment air valve can be centrally controlled to achieve continuous alignment and stable alignment. However, maintenance of the membrane air chamber and gear train should be strengthened.
(7) Transmission device: Due to the wide speed range (from “inch row” to 120m/min), the transmission of the printing combined machine generally uses an AC commutator motor. After being reduced by the reducer, the central gear is driven. Then the flower tube is driven, and then the drying, cloth discharging and other parts are driven by the passive pressure roller. That is, the overall transmission method is adopted, as shown in Figure 8-17.
In order to facilitate the coordination of the speed of the printing and drying parts, the central gear shaft is now often used to drive the drying part through a chain, with a speed adjustment device installed in between. In addition, the drying part is also equipped with a special motor for independent transmission to facilitate preheating, cleaning and troubleshooting. In recent years, most of the main parts of the printing combined machine adopt electromagnetic slip clutch and DC motor to drive independently, and automatically adjust the speed synchronously, that is, the multi-unit machine is driven independently.
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