Four-color machine circuit failure

The Rapida 104's 4 ink fountain rollers are driven by a DC motor, using thyristor stepless speed regulation, convenient and quick adjustment. In order to reduce the net height of the machine, four ink roller DC motors are mounted laterally above the machine transmission surface. After long-term use, the reduction gearbox seal directly connected to the DC motor wears, and the oil in the gearbox flows into the motor, causing the brush to accumulate oil and electricity. The leakage current generates high heat, which causes the brush to become carbonized and exacerbates the leakage. The generation of the thyristor stepless speed regulation circuit is accompanied by frequent failures such as burning a fuse, firing a thyristor, and burning a printed circuit board. In order to completely solve this problem, two methods can be taken:

(1) The DC motor was changed to a vertical installation, a gear box was placed underneath, and the motor was on. The oil leakage phenomenon was completely eliminated, and the oil pollution did not accumulate on the brush holder. This resulted in another advantage: The space between the units is large, and it is easier to get in and out. After the motor is installed upright, the original wiring is short, and it is necessary to take long lines. It is recommended that the manufacturer leave the wires when producing the offset press to facilitate the user's modification.

(2) Since the brush holder has been carbonized, a new brush holder can not be bought at home for a while. Therefore, the carbonized layer on the brush holder must be scraped off, coated with insulating paint, and then put on the handle for reuse. In order to prevent the brush from being broken down again by the voltage, a method of reducing the voltage is adopted. An isolation transformer is inserted between the power supply and the thyristor circuit. The isolation transformer can be wound by itself. The input voltage is 220V, the output voltage is 80V+80V, and the power is 1000W. The center of the output winding is grounded. Two 80V output terminals are connected to the thyristor speed control circuit. In this way, the voltage applied to the brush holder on the DC motor is reduced by more than half and the failure rate is greatly reduced.