Offset press has a wide variety of brakes, according to its role can be divided into positioning, limit, protection of three categories, there are absolutely static, there are relatively static, under normal circumstances is a double appearance, but also by the brake Screws are used in combination with each other. It is very important to rely on the correct position of the brake and adjusting screw. This article will take the North J2205, PZ4880-01B four-color machine as an example to analyze its function, adjustment method, and various failures caused by it.
1. The paper feeder has two roles: the brake lever on the brake paper feed roller shaft, which can control the magnitude of up and down movement of the paper take up roller, and can control the length of the paper press time. When adjusting, pay attention to both Coordination of relations.
2. The front gauge is determined by the brake positioning (J2205). During the operation of the machine, the loosening of the tightening nut on the inside of the operating surface should be prevented.
3. The paper-feeding mechanism depends on the brake. The paper-delivery mechanism has two brakes: First, there is a symmetry brake on the left and right sides of the paper conveying tooth shaft, which is the reference for adjusting the opening and closing amplitude of the gripper. Adjustment method is: on both sides by the brake pad thick 2mm paper, adjust the teeth after removing the paper. The second is the reversing brake on the rowing arm, which has positioning and shock absorption. When adjusting and controlling its positioning screws, special care should be taken to adjust the length of the delivery tooth row on the dental table for a long time. If the retention time is short, the registration accuracy will be affected. The correct adjustment method is to twist the brake screw so that the swing arm of the swing arm is about 0.08 mm away from the swinging cam. At this time, strict attention should be paid to the position where the two sides are separated and entered the contact point (to ensure that the delivery tooth row stays on the dental table for 27°); both sides must be on the brake while escaping at the same time, otherwise swinging the paper teeth on the tooth base When the stacking paper is unstable, the pick-up range is also inconsistent, and it is prone to inaccurate longitudinal misprints. The above problems are mainly caused by the J2205. This part of the PZ4880-01B four-color machine has only one brake on the inner side of the operation surface. Its positioning effect has disappeared because the delivery mechanism uses an equidistant conjugate cam and cam. The design and machining accuracy has reached the requirements, so the brakes only play a protective role.
4. When the water transfer roller and the ink transfer roller shaft depend on the brake to transfer water and transmit ink, the brake should be in contact with the brake screw. When the water is connected and the ink is connected, the two should have gaps under the action of the tension spring. Here, it is easy to accumulate ink, dust, and other dirt. Failure to clean it in time will affect the gap between activities and cause difficulty in receiving water and ink. Attention should be paid to it. Always clean and diligently add fuel.
5. The effect and adjustment method of the press roller squeezing the pinion shaft is the same as the brake on the transfer paper sprocket shaft. It should be noted that after disassembling and repairing the squeezing tooth shaft, the squeezing screw shall be screwed and the squeezing shaft shall be put on the shaft. The distance between the opening and closing tooth bearing and the shoulder roll of the impression cylinder is adjusted to 13±0.05 mm. All the clamps on the shaft must be loosened during the calibration. After adjusting the brake position, adjust each tooth again.
6. Coupling presses against the brakes. Coupling presses against the limit of the brakes to prevent over-compression and excess pressure. Care must be taken when adjusting. When adjusting, firstly press the brake screw and the pressure release brake screw loosely; press and press together, when the largest surface of the pressure cam comes into contact with the roller, turn the pressure and press the brake screw to make the clearance with the brake. 0.08mm, then pressure; When the largest surface of the pressure cam and the roller contact, adjust the pressure and rely on the brake screw by the brake gap to 0.02mm is appropriate. Why is the pressure clearance large? This is because when the offset press is operated, the pressure is applied at a low speed, and the pressure is released at a high speed. The clutch shaft has a large inertia at high speed, so the pressure is generally depended on the pressure. The gap between the brake and the screw should be slightly larger. In the J2205 two-color machine, two groups of clutch pressures are not synchronized, that is, when the upper group is one beat at a time, and the next group is one beat at a time (relatively speaking), the first print is printed on the second color and the first color is not printed. . This fault is mostly caused by improper clearance between the two groups of clutch press brakes and brake screws, as long as careful adjustment, this fault will disappear.
7. The role of the take-up teeth row on the brake lever is the same as that on the feed shaft.
During the operation of the offset press, it is necessary to constantly observe whether these brakes are in the correct position and whether the brake screws are loose, and try to eliminate the fault in the bud.