Vacuum Printing Machine of Offset Printing Machine: Common Faults and Remedy

Offset printing machine vacuum suction device is composed of high-speed direct vacuum pump and three-phase motor, in addition to rubber pipes, solenoid valves, valves, pressure gauges and other accessories.

The vacuum pump of the offset printing plate is composed of a stator, a rotor and a rotary vane. The rotor is eccentrically mounted in the cylinder, two rotor blades are installed in the rotor groove, and the cylinder wall is abutted by the elastic force of the spring. Therefore, the inlet and outlet ports of the stator are separated into two parts by the rotor and the rotor. When the rotor rotates in the cylinder, it periodically expands the volume of the intake port to inhale the gas. At the same time, it gradually reduces the volume of the exhaust port, compresses the inhaled gas and discharges it from the exhaust valve, thereby achieving pumping. purpose.

The common fault of the vacuum pumping device of the offset printing platen has two aspects: First, the vacuum degree of the vacuum pump of the plate printing machine is reduced; second, the problem of oil leakage of the vacuum pump.

1. Spiral plate pump vacuum pumping is insufficient, the degree of vacuum is reduced, often easily caused by the film surface of the film or the positive image of the laser printer output is not close between the sulfuric acid paper and the PS plate, absorption is not true, the sun out of PS version can not guarantee the quality, text, lines, images, and dot transfer to the printing plate can not reach the requirements.

The quality of the offset vacuum stencil printer depends on two factors: First, the film surface of the sensitized film is closely aligned with the PS plate, and there is no slightest gap. This requires the vacuum pump to work properly. The pumping rate is about 2 to 4 liters/sec. Secondly, when the PS version is exposed, the blue-violet illumination is uniform on the entire glass surface around the edges and the middle area. This is a measure of the performance of the offset printing machine. standard.

The reasons for the lack of vacuum pumping efficiency of the plate-making machine vacuum pump are as follows:

(1) Gas pipeline leaks due to rat bite, aging, and rupture;

(2) Shaiban printing frame elastic rubber sealing cloth mat aging rupture leakage;

(3) The rubber pipeline for gas transmission is too long, and the gas consumption affects the vacuum scheme;

(4) Insufficient oil in the vacuum pump;

(5) Too many impurities in the vacuum air pump

(6) The vacuum pump seal wears and leaks and leaks oil;

(7) Blockage of the delivery hole in the pump or insufficient oil supply;

(8) exhaust valve sheet wear and damage;

(9) The rotor spring breaks.

Correspondingly, the solutions to these failures are:

(1) Replace damaged rubber pipes;

(2) Use tape or tape to stick to the leaking place of the elastic rubber sealing cloth mat in the frame. Pay attention to maintenance every week. Wipe the rubber frame with glycerin to prevent aging. Keep the elasticity of the blanket frame and reduce the frame leakage. Gas problem

(3) The length of the rubber pipeline for gas transmission shall not exceed 2 meters and the gas consumption on the pipeline shall be avoided.

(4) Add new vacuum oil to the centerline of the oil standard;

(5) Replace with fresh vacuum oil;

(6) Replace with new seals or readjust assembly;

(7) Clean the oil inlet hole;

(8) Replace the new exhaust valve piece;

(9) Replace the new rotary spring.

In addition, the gas path should be kept clean, and there should be no dust or any foreign material on the inner wall of the pipeline. It is usually cleaned with a fine wire to keep the pumping line of the hose clear.

At the same time, pay attention to the positive and negative rotation of the vacuum pump three-phase motor, motor phase circuit installation will be reversed misplaced, vacuum pump gas pipe may be blowing, this time, must be replaced at the motor connection phase, so that the vacuum pump suction .

2. The offset pump vacuum pump oil spill is often encountered. The main reason is that vacuum pump shafts and oil seal fittings are used for many years, resulting in the wear of the seal ring. When the oil leakage is severe, the newly injected vacuum oil leaks a large area of ​​oil after a while, polluting the environment and affecting the normal operation of the vacuum pump. When repairing, reduce the coil or replace the oil seal. When disassembling the assembly and repairing, sealant is applied on the sealing gasket to prevent oil leakage and air leakage. In addition, the damage to the gasket at the connection of the vacuum pump tank can also cause oil leakage. The solution is to replace the gasket. Do not add excessive amount of vacuum pump oil, align the oil level line. If the vacuum oil is added too much, the vacuum pump will splatter and throw out the oil when working.

Keep the exhaust system function intact in daily work. The vacuum pump should be checked once a week. The oil level should always be aligned with the oil level. New vacuum oil must be replaced every year for one year.

The vacuum pump and the motor are generally installed at the back of the plate, the vacuum pump and the surrounding environment of the motor should always be kept clean to reduce dust and debris to the pump body and the motor. At the same time, it must be able to ventilate and heat the vacuum pump. Each year must be dismantled and repaired on a regular basis.

The rubber hose from the suction frame of the printing plate under the printing plate to the suction nozzle of the vacuum pump can easily be sucked and damaged when it is used for a long time. It should be replaced in time to prevent air leakage.

The surface and back of the glass platen must be kept clean. When wiping, clean it with a soft brush first, then wipe with a non-abrasive cotton or gauze.