How to eliminate the printing plate œ Common faults
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There are many types of printers, and the light sources used are different. Here we introduce the structural characteristics of the box-type printing machine, and describe some different characteristics of the various box-type printing machines and common faults.
The shape of the box type printing machine is a cubic structure, the upper cover is a blanket sealing frame and the periphery of the seam is sealed by a rubber strip, and has a handle, which can be picked up. The trachea is connected to the vacuum pump. Between the box and the lower case, there are locks on the front, hinges on the back, and struts on both sides. Under the sealing cover, there is a flat glass with excellent transparency and uniform texture and a thickness of about 10 mm. An exhaust fan is installed behind the cabinet. The middle part is a light box with an iodine gallium light source or a halogen light source. Around the light source is a reflector with reflected parallel light. The precision screen exposure machine uses a photoelectric integrator to control the brightness and has the function of automatically limiting the exposure time. Ordinary screen exposure machines use a set standard number of seconds to limit the exposure time.
When the screen is needed, the blanket frame is uncovered, and the photographic film is first attached to the surface of the parallel glass plate, and then the screen printing surface coated with the photosensitive glue is pressed against the film surface of the film, and then the rubber is covered. Cloth frame, start vacuuming, use the shrinkage of the blanket, attach the mesh surface and the negative film firmly to the glass plate, open the exposure light source with a certain wavelength, set the optimal exposure time, and the exposure time is up. The light source is automatically turned off. It can also be switched from manual operation to manual operation.
The quality of a printing machine depends mainly on three factors. The first is whether the vacuuming machine system of the printing machine can make the photographic film and the photosensitive material on the screen close to each other without leaving any gaps; At the second exposure, the illuminance of the middle of the entire layout and the position of the four peripheral edges are uniform. The third stable performance control circuit and the stable and durable exposure light source during exposure.
The symptoms of the different types and characteristics of the box-type printing machine are also different. But no matter what kind of problem will directly affect the quality of plate making. The following describes the structural characteristics of several different types of printing machines and the analysis and elimination of faults.
First, the common faults that will occur in several printing machines include:
1. Due to insufficient suction or no suction, the photographic film and the mesh photographic material cannot be closely attached to the glass plate, causing the plate to appear disqualified screens such as walking, distortion, jaggedness, and ambiguity.
The printing machine has the reasons of insufficient suction or no suction. The main analysis steps are as follows: The preliminary judgment method is to separate the vacuum pump from the air pipe, block the suction port of the vacuum pump with the thumb, and observe whether the barometer pointer points to the maximum value. If the maximum value indicates that the vacuum pump is operating normally, it should be judged that there is a leak in the trachea and blanket (including: the blanket has a trachoma leak; the seal strip is not well leaked; the cover is tightly adjusted) The screw is not properly adjusted, and there will be air leakage when loose and tight; the interface of the suction pipe is loose and the air leaks. If the pointer of the barometer is not reflected or is small, it means that the vacuum pump is not working properly. The fault phenomenon includes: the vacuum pump motor coil burns out and stops, the vacuum pump has no oil, causing the stuck stop operation, the blade inside the vacuum pump is damaged, and the suction is insufficient. Reasons)
2. After using the printing machine for a certain period of time, it feels that the actual exposure time is much longer than the expected exposure time.
(1) The exposure lamp has weakened energy for a long time, and the lamp must be replaced.
(2) Even if a new lamp is replaced, the exposure time is still long. At this time, first consider the cleaning inside the box; secondly, consider whether the reflector has a good reflection effect, and the light transmission effect of the glass plate; secondly, it is necessary to consider whether the quality of the new lamp replaced is problematic.
Second, the different characteristics of various printing machine, fault analysis and elimination:
1, SWE1100 type printing machine, the power is 2KW.
It adopts relay control circuit and push button operation panel. It has functions such as vacuum pumping and exposure timer. Manually inhale and expose, and stop automatically according to the timing.
Common fault: The panel power indicator is on but it cannot be started.
Fault check sequence:
A, insurance burnt out; B, AC contactor contact carbonization, poor contact or coil burnout; C, thermal relay automatically trip; D, vacuum pump burned or stuck; E, exposure lamp burned; F, rectifier, The trigger is faulty.
2, SWE1200A type printing machine, the power is 3KW. Microcomputer control with ten memory channels. There are two kinds of imported oil-free silent vacuum pumps and ordinary domestic vacuum pumps. Board control circuit, touch panel. After the exposure time is set, the time is not the standard number of seconds, but the photoelectric integrator is used to control the brightness, and the exposure time is automatically limited to compensate for insufficient light. Easy to operate, not affected by lamp aging and operator experience. Suitable for the production of fine lines, dot patterns, and circuit board screens. Practical economy. With automatic and manual exposure. When it is automatic, it has the function of secondary pumping after pre-pumping, and the preset pumping time is up to automatic exposure. The preset exposure time is automatically stopped. The manual mode is manual start and manual stop.
Fault phenomenon analysis:
A. The number on the operation panel is weak or incomplete. Due to damage to the rectifier bridge, the 5V DC input voltage of the operation panel is not enough or the (7805) triangular regulator fails.
B. The suction pump and exposure lamp cannot be turned on. The 24V output voltage of the rectifier bridge, the (7824) delta regulator or the IC integrated block is broken through;
C. It is impossible to achieve secondary inhalation when it is automatic, that is, the suction of the blanket does not affect the plate making. The solenoid valve above the vacuum pump is dropped, burned out or the control relay is damaged;
D. The UV lamp is a negative resistance gas discharge device. Regardless of the good ring, it is open circuited with a multimeter. Under normal circumstances, even if it is damaged, it is open circuit and will not affect the circuit, but it is likely to be under high pressure. A short circuit or a very low internal resistance will occur. At the end of pumping, the control circuit is turned into the working state, and the high voltage of the output of the step-up transformer is instantaneously applied to both ends of the lamp tube. Due to the short circuit or the internal resistance is extremely low, the strong inrush current causes a very high self-inductance potential to enter through other lines. The control loop causes a fault. At this time, the microcomputer control circuit board is faulty and the rectifier bridge is excited. This type of fault is a special case.
3, W-SP-3648A/4860A precision screen version of the printing machine, the power is 3KW. Microcomputer control with twenty-five memory channels. Equipped with oil-free silent vacuum pump. Board control circuit, touch panel. The conversion of standard seconds and accumulated exposure time can be realized. When the volume exposure is used, the time is not the standard number of seconds, but the photoelectric integrator is used to control the brightness, and the exposure time is automatically limited to compensate for the lack of brightness. Easy to operate, not affected by lamp aging and operator experience. With automatic and manual exposure. The manual mode is manual start and manual stop. In addition to replacing the exposure tube for normal usage, other failure rates are minimal.
The lamp can be started continuously, that is, it takes only 3 to 5 seconds for each stop and start interval.
Suitable for the production of fine lines, dot patterns, and circuit board screens.
Excellent material selection, reasonable design and beautiful appearance.
In short, no matter which one of the drying machine is used, or the kind of fault encountered in the work, we must understand and understand the machine performance principle and the cause of the malfunction, and prescribe the right medicine. In daily work, care should be taken to maintain and maintain. Check the pumping system frequently. The vacuum pump should be inspected once a month and vacuum oil should be added regularly. Clean the suction pipe and keep the suction hose free from dust and debris. The surface of the glass should be absolutely clean. Wipe clean with a cotton wool, gauze and anhydrous alcohol. The point source and reflector should also be kept clean. Regularly change the exposure light source to avoid the light intensity of the light source is weakened, and it is not appropriate to grasp the exposure time and affect the plate making quality.