Cloth moving flat screen printing machine
The cloth moving flat screen printing machine adopts computer control technology to realize automatic cloth feeding, automatic cloth patching, automatic lifting and lowering of the color frame, automatic scraping and printing, automatic drying of fabrics and automatic cloth discharging, which reduces the operation It reduces the labor intensity of workers and improves production efficiency. It is a type of flat screen printing machine that is currently used more frequently.
11 Working process and structure
Cloth moving flat screen printing machine is to paste the fabric on a straight and seamless annular guide belt that circulates along the warp direction. It runs intermittently with the guide belt, and the color frame is fixed at a certain position. The position is suitable for lifting and leisure. When the guide belt is stationary, the color frame descends, and the scraper reciprocates to scrape and press the color paste, so that the color paste passes through the mesh and is printed on the fabric. After scraping printing is completed, the color frame is lifted, and the fabric moves forward with the printing guide belt for a flower return distance (equal to the length of the pattern in the screen). The printed fabric is pulled up from the guide belt at the end of the printing unit and enters the dryer to be dried and then dropped. When the guide belt runs to the non-printing area, the cleaning device removes the color paste remaining on the guide belt to prepare for the next printing cycle.
The cloth moving flat screen printing machine automatically completes the following actions in each printing cycle:
The guide belt travels → the belt stops → the color frame drops → the scraper scrapes and prints → the color frame lifts → the guide belt travels →…cloth The dynamic screen printing machine is generally combined with other unit machines and general devices to form a printing combined machine, which is composed of a cloth feeding device, a printing unit, a drying and cloth discharging device, as shown in Figure 8-18. The printing unit is the core part of the cloth moving flat screen printing machine. It is mainly composed of a cloth pasting device, a cloth guide mechanism, a color frame lifting mechanism, a squeegee mechanism, a cleaning mechanism, etc.
(1) Fabric feeding device: roll feeding and folding fabric feeding can be adopted as needed. The fabric passes through the guide roller, fabric tensioner, elastic adjustment roller (tension compensation device) and edge suction device to ensure that the fabric enters the machine with low tension and flatness. The tension compensation device adjusts the infinitely variable speed DC motor to synchronize the movement of the fabric with the printing guide belt; the disc-type compressed air edge stripper can remove the curling of the fabric, which is very suitable for knitted fabrics that are easy to curl and have high stretchability; the electricity is completed The edge suction device can remove wrinkles from the fabric surface and prevent fabric deviation under the control of electric eyes on both sides. If printing narrow-width fabrics, the fabric can also be fed in double widths.
In the cloth feeding unit, a cyclone dust collection device can also be used. It removes dust, fluff and yarn ends on the fabric through the alternate use of beating and brushing, and then uses a powerful exhaust device to remove the dust and fluff through the air. collected in the dust collection box.
(2) Cloth patching device: In order to stick the fabric flatly on the guide belt, water-soluble pulp patching and thermoplastic resin patching are usually used. And they need to use two sets of completely independent patching devices.
The water-soluble pulp pasting device, as shown in Figure 8-19, is a two-roller pulp feeding device. The pulp feeding rollers evenly transfer the water-soluble pulp in the pulp tank to the surface of the printing guide belt. The fabric is pressed It is flatly adhered to the guide belt under the action of rollers. The thickness of the sizing layer can be adjusted according to different fabric specifications and varieties by adjusting the gap between the sizing roller and the guide belt. Suitable for hydrophilic fabrics and flat screen printing machines with narrow width.
The thermoplastic resin patching device, as shown in Figure 8-20, uses a hot pressure roller to make the fabric close to the thermoplastic resin PU coating. layer of printing guide tape. The hot pressing roller is a seamless steel pipe with an electric heating element inside to heat the steel pipe. The temperature is generally in the range of 40 to 80°C and is controlled by a temperature control device. Since the conductor belt runs intermittently and the hot pressure roller continuously exerts pressure on the conductor belt, it can easily cause uneven heating of the conductor belt. Therefore, the linear pressure of the hot pressure roller and the running speed of the guide belt must be interlocked, that is, the linear pressure of the pressure roller changes with the change of the running speed of the guide belt. When the speed of the conductive belt is high, the pressure is high; conversely, when the speed is low, the pressure is low. The thermoplastic resin patch lovingly protects the surface of the conductor belt, extending the service life of the conductor belt and compensating for minor damage to the conductor belt. It is suitable for any fabric and flat screen printing machines of various effective widths, and is very suitable for hydrophobic fabrics.
There are two types of thermoplastic resin: N type and I type. Type N is suitable for summer use and has poor viscosity; Type I is used for general seasons and has good viscosity but poor heat resistance. It has no viscosity when not heated, so it will not adhere to impurities such as dust and fluff after parking.
(3) Cloth guide mechanism: The cloth guide mechanism consists of a printing guide belt and a guide belt transmission system. The function of the printing guide belt is to send the fabric from one screen frame to another in a fixed length. The printing guide belt is a seamless ring-shaped rubber guide belt made of multi-layer canvas coated with rubber. The printing guide belt accurately controls and adjusts the running distance and pause position according to the size of the flower loop, and can make acceleration, deceleration, braking and automatic cycle actions. The printed fabric is always stuck flatly on the printing guide belt and runs and stops with the guide belt. The guide belt is supported by a flat table.
The belt drive system is the key to determining the quality and accuracy of printing. The guide belt is required to be accurately positioned during transmission without any deviation. The transmission methods of the guide belt are divided into two categories: mechanical transmission and hydraulic transmission. The mechanical transmission is driven by a variable speed motor through a reducer to the guide belt pulling roller at the cloth end, and the printing guide belt is driven by friction on the surface of the pulling roller; the hydraulic transmission adopts hydraulic pressure The cylinder connects the guide belt holder to clamp the edge of the guide belt and push the guide belt. The mechanical transmission structure is simple, easy to manufacture, and consumes less power, but it suffers from mechanical wear and tear.��, the alignment accuracy is poor; the hydraulic transmission alignment accuracy is high, the degree of automation is high, it is convenient for centralized control, and the operation is convenient, but the power consumption is large.
Figure 8-21 shows the schematic diagram of the hydraulic transmission for intermittent operation of the guide belt in the printing area. The piston of the oil cylinder is fixed and the cylinder body moves. The cylinder body is connected to several sets of guide belt holders in the left and right rows through connecting parts. When oil enters the A side of the cylinder piston (the pressure oil flows in through the one-way valve D), the cylinder block is pushed to move to the right. At this time, the clamper 3 clamps the edges on both sides of the guide belt and runs synchronously with the cylinder block. At this time, the return oil on the B side of the piston directly passes through the stroke throttle valve C, which can return a large amount of oil, and the guide belt is in the high-speed traveling stage. Before the guide belt travels close to the end of a flower return (position shown in the picture), the slope of the cylinder contacts valve C, and the oil return volume on side B gradually decreases, and the guide belt gradually slows down until valve C is completely closed, and the oil return Returning to the fuel tank through the throttle valve C, the guide belt is crawling at a slow speed. The end of the rear cylinder contacts the positioning stop 5, and the cylinder travel stops (at this time, the main control valve E is in the middle position), and the guide belt is completely stationary. The tape travels a fixed distance each time. When the main control valve is shifted to the return position, the B side of the piston enters oil, the A side returns oil, and the cylinder moves quickly to the left. At this time, because the holder loosens the guide belt, only the holder itself returns with the cylinder. in place, while the conductor band remains motionless.
There are many types of guide belt holders, and the commonly used ones are electromagnetic clamps, pneumatic clamps, etc. There is also a vacuum suction cup, which is sucked under the conductive band along the entire conductive band. As shown in Figure 8-22, it is a cross-sectional view of the electromagnetic clamp commonly used in current hydraulically driven flat screen printing machines. When it is necessary to clamp the conductive tape to move forward, the coil 3 is energized and attracts the magnetic pole clamping plate 4, so that the top of the clamping plate is pressed against the top surface of the clip base 2, thereby firmly clamping the edge of the conductive tape and allowing the conductive tape 5 to follow the electromagnetic clip. The purpose of designing the magnetic pole splint to be tilted is to maintain a small suction distance and ensure a sufficient breakaway distance for the conductor belt.
Figure 8-23 shows the schematic diagram of continuous operation of the guide belt in the non-printing area. In the picture, the printing guide belt maintains intermittent operation in the printing area above the platen, while the guide belt in the non-printing area maintains continuous variable speed operation. In this way, the fabric can be continuously input under small tension and evenly adhered to the surface of the guide belt at the cloth inlet end. The printed fabric is also continuously peeled off the guide belt at the cloth outlet end and then sent to the dryer for continuous drying. dry. The slight difference between the intermittent printing in the printing area and the continuous printing in the non-printing area in each printing cycle is automatically compensated by the wandering roller I at the cloth inlet end and the wandering roller II at the cloth outlet end. Its working principle is as follows:
The printing cycle starts. The printing guide belt is clamped by the clamper. Driven by the oil cylinder, it travels for a flower return length at the speed of va. At this time, the continuous return speed of the guide belt vr is less than va, so the wandering roller I moves from the position A moves vertically downward to A′. Under the action of traction chain 2, roller II moves horizontally from position B to B′. When scraping printing, the printing area guide belt is stationary (va = 0), while the non-printing area guide belt is driven by the driving roller 4 controlled by a hydraulic variable speed motor and is continuously fed back to the guide belt at a continuously changing vr speed. Therefore, roller II is pulled back to the original position B from position B’ by the guide belt, and roller I also returns to the original position A from position A’.
(4) Color frame lifting mechanism: During printing, the color frame automatically drops to contact with the fabric and is pressed tightly before the color paste can be scraped and printed. After scraping and printing is completed, the color frame needs to be immediately raised to a certain height and completely separated from the printed fabric. The printed fabric then travels with the guide belt for a flower return length.
Therefore, the lifting and lowering of the color frame must be coordinated properly with the operation of the guide belt and the reciprocating movement of the scraper. The color frame must be raised and lowered smoothly. Therefore, for screens with larger effective width or larger flower return, in order to prevent color paste from splashing between the bottom surface of the screen and the printed fabric, the partial lifting method is often adopted, that is, the flat screen on the transmission side is lifted first, and then the lifting operation is performed. The side of the screen is flat to reduce screen vibration and prevent color paste from splashing. In terms of the descending speed of the color frame, in order to shorten the time required for each printing cycle, a two-drop method can be adopted, that is, when the color frame first descends at a high speed to about 10mm from the surface of the fabric, it pauses the descent, and then descends again after the fabric stops.
The lifting and lowering of the screen frame can be driven by an electric motor or a hydraulic cylinder, and is accomplished through a crank slider or a swing-bar connecting rod mechanism. There are also mobile cam lifting mechanisms driven by a cylinder. Figure 8-24 shows the schematic diagram of the cylinder-driven connecting rod screen lifting mechanism.
This mechanism uses a double-piston oil cylinder, in which the inner and outer pistons are connected to the swing rods on the operating side and the transmission side of the screen bracket respectively. The connecting rod 5 of the outer piston 7 is connected to the swing rod 1 on the transmission side, and the inner piston The connecting rod of 8 is connected to the swing bar on the operating side, so it can meet the requirements of horizontal or partial lifting of the screen required by the process. When the internal and external pistons of the cylinder expand and contract synchronously, the swing rod 1 swings around the axis, and the drawbar 2 moves horizontally. Through the four-bar linkage 4, the screen brackets 3 on the operating side and the transmission side are raised and lowered synchronously to achieve the general screen level. l requirement. When printing wide-width fabrics, the outer piston 7 moves first to lift the transmission side screen first. When it reaches a certain height, the inner piston 8 moves again, so the screens on both sides rise synchronously to meet the screen upward requirement.
(5) Squeegee device: The squeegee device is an important unit that directly affects the printing quality. It is divided into rubber squeegee (squeegee for short) ) type and magnetic squeegee roller (referred to as magnetic roller) type.
①Scraper-type scraping device: As shown in Figure 8-25, the scraper-type scraping device consists of a transmission box, a guide frame, a slide, a scraper, and a color frame.It is composed of color frame adjustment frame, etc. The transmission box adopts a variable frequency motor for speed regulation, which is used to control the reciprocating scraping and blade changing actions of the scraper slide; the scraping speed, stroke, number of times and overprint (floating scraping) can be set by the buttons on the operation panel. The scraping speed It is 0.4~2.2m/s, divided into 10 levels. The pressure, angle and height of the scraper can be manually adjusted through the corresponding rotating handle on the slide seat. The adjustment range of the scraper angle is 25°. Generally, double scrapers are used to scrape in the latitudinal direction, and the number of scrapings is 1 to 8 times. The color frame adjustment frame is used not only to support the color frame, but also to adjust the high, low, vertical and horizontal positions of the color frame to align the color registration. The function of the color frame reducing frame is to hold different door width color frames to meet the needs of narrow fabric printing.
②Magnetic roller scraping device: The magnetic roller scraping device consists of a guide frame, a color frame, a color frame adjustment frame, and a metal roller It is composed of a magnetic device (magnetic box for short). Under the action of electromagnetic attraction under the guide belt, pressure is generated between the metal roller and the screen. When the magnetic device moves, a pair of force couples are formed due to the horizontal force component of the electromagnetic attraction on the center of the metal roller and the frictional resistance of the screen to the surface of the metal roller. , so that the metal roller rolls on the surface of the screen with the movement of the magnetic box. The magnetic box can be pushed by a hydraulic cylinder or driven by a reciprocating screw driven by an electric motor.
The structure of the magnetic roller scraping device is simple. It uses meridional scraping, which has better uniformity than scraping along the width direction. There is rolling friction between the scraping roller and the screen surface, which can extend the service life of the screen, but it is not good for metal The roller’s straightness and surface roughness are required to be high, and the squeegee speed of each color squeegee roller is consistent. Unlike squeegee squeegee printing, the squeegee speed or the number of squeegee times cannot be adjusted separately according to process needs.
(6) Cleaning mechanism: During the printing process, the color paste often seeps from the front of the cloth to the back and contaminates the guide belt. There are also adhering fluff and other dirt, which must be cleaned in time. Therefore, a water washing device for the guide belt is installed in the non-printing area of the guide belt. It consists of sprinkler, water tank, wiper, etc. The first condition for uniform cleaning is that the guide belt must be continuously relaxed. The printing guide belt is pre-sprayed by the sprayer.
A soft foam pad is used to wipe away the remaining color paste, and a plastic scraper is used to scrape off most of the dirt. Then use the pre-cleaning brush to roughly clean the residual substances on the guide belt. After scraping with a scraper, scrub again with the second brush. The scraper pressurized by compressed air scrapes away the remaining water.
The water tank is made of stainless steel sheet. The water level in the water tank is continuously monitored by sensors. For easy cleaning, the water tank can be completely pulled out from the side of the machine. The foam pad and wiper blade can be pulled out for inspection at any time.
(7) Floral cloth drying machine: After the printed fabric is separated from the printing guide belt, it is sent to the conveyor belt of the floral cloth drying machine for tension-free drying. The conveyor mesh belt is made of polyester monofilament and has a rough surface and high air permeability. During the drying process of the fabric, no matter how the thickness of the fabric, the density of the tissue and the permeability of the printing paste change, it will not cause “color matching”. Figure 8-26 shows a form of flat screen printing dryer. Due to the low speed of the flat screen printing machine and the small amount of fabric in the drying room, 2 to 3 layers of fabric are generally put through. The hot air circulates throughout the machine, and the fabric enters and exits at the same end, making it easy to operate. The floral fabric is supported by the conveyor mesh belt and enters the drying room. The angle of the inclined cloth feeding rack can be adjusted appropriately as needed. The linear speed of the conveyor mesh belt and the linear speed of the printing guide belt conveying the fabric are synchronized. They are automatically detected by infrared power after completion. Adjustment. The heat source of the dryer is generally saturated steam, but superheated steam or high-temperature heat-carrying oil can also be used. The maximum working temperature of the drying room is 120 to 150°C, which is automatically controlled by the temperature control device.
21 Start-up planning, operation and parking
(1) Plan the printing process according to the process and sample requirements.
(2) Determine the number of threads and connect the cloth guide belt according to the product condition.
(3) Adjust the gluing range and glue thickness.
(4) Adjust water washing.
(5) Match the flowers.
(6) According to the process requirements, sharpen the blade of the scraper and equip a color paste bucket as needed.
(7) Connect the white cloth and the end of the cloth guide belt, push up the gluing mechanism, and start the machine according to the electrical program. Hot air circulation, drying room heating.
(8) After one cycle of printing is completed, the front end of the floral cloth is connected to the cloth guide belt in the drying room, and the linkage clutch of the drying room is operated to guide the floral cloth into the drying room for drying.
(9) During the printing process, the following conditions should be paid attention to and corrected:
① Whether the position, tension and spring expansion roller of the cloth are appropriate.
② Whether the scraper stroke, scraping times, scraper height and pressure, scraper edge shape and angle are appropriate.
③Be careful that the two ends of the scraper cannot rub against the inner edge of the screen frame when the scraper reciprocates radially.
④Whether the alignment and detector positions are accurate.
⑤ Pay attention to the splash spots on the cloth surface, the penetration of the cloth edges, the “up delay” time and the position of the edge roller, etc. If there are any problems, adjust them in time.
(10) When printing is about to end, connect the tail end of the white cloth to the cloth guide tape.
(11) When the tail end of the white cloth enters the color registration position, the gluing mechanism can be put down and cleaned.
(12) When printing ends and leaves the printing screen frame, you can turn the knob switch for each number of scraping times to “0” one by one according to the program, let the scraper stop one by one, and then remove the scraper one by one.��, printing screen frame and pulp barrel, clean and properly place them.
(13) After printing a set of color positions, the tail end of the patterned cloth can be connected to the guide belt of the drying room. After the patterned cloth enters the drying room, the patterning (power-up) system can be turned off to allow the guide belt to Run alone to clean the slurry on the surface of the guide belt.
(14) When the scraper, screen frame, and slurry bucket are all removed, and the surface of the guide belt is clean, close the water inlet valve, put down the water washing box, and stop the machine, but the screen frame must be left in the rising position. starting position. Stop heating and cut off the fan power supply depending on the condition of the drying room.
(15) Clean the fuselage and site, check the condition of the entire machine, and keep it in normal condition.
31 Maintenance
(1) When the electric tube is damaged, the alignment is inaccurate and the electric control fails. It is necessary to replace the electric sensitive diode or adjust the electric head.
(2) When the lifting travel switch fails, the machine stops or the movement is disordered. It is necessary to check whether the contact of the travel switch is good.
(3) When the scraper action fails, the travel switch should be checked. If the number of scratches is incorrect, the counting device is faulty. The scraper has no delay, the delay relay should be checked.
(4) The electrical components of the entire machine must be inspected once a week to see if they are working properly, if the screws are loose, if the contact is good, etc.
(5) If the temperature of the drying room is not enough and the cloth does not dry out, you can choose “up delay” or “down delay” for appropriate delay, or start the exhaust to remove water vapor.
(6) In case of an accident, press the “Emergency Stop” button and the machine will stop running immediately. If the fault cannot be solved within 5 minutes, the heating should be stopped to prevent the fabric from drying out.
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