Talking about the function of the offset press and the adjustment method
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The offset printing machine has a variety of brakes. According to its function, it can be divided into three categories: positioning, limit and protection. It is absolutely static and relatively static. Under normal circumstances, it is double-folded, and all have brakes. The screws are used together and the two do their best. It is very important to adjust the position of the brake and the adjustment screw. This paper will analyze the function, adjustment method and various faults caused by the Beiren J2205 and PZ4880-01B four-color machine.
1. Feeder brake
The brake on the paper feed roller shaft of the paper feeder has two functions, which can control the magnitude of the up and down movement of the paper take-up roller, and can control the length of the paper pressing time. The adjustment of the relationship should be paid attention to when adjusting.
2. Front gauge brake
The front gauge relies on the brake positioning (J2205). During the operation of the machine, the loosening nut on the inner side of the operating surface should be prevented from being loose.
3. Transfer mechanism
There are two brakes in the transfer mechanism: First, there is a symmetrical brake on the left and right sides of the transfer head, which is the reference for adjusting the opening and closing amplitude of the gripper. The adjustment method is as follows: a paper strip with a thickness of 0.2 mm is placed on the two sides of the brake, and the paper strip is taken out after the tooth decay is adjusted. The second is the brake on the arm of the transfer paper, which has positioning and shock absorption. When adjusting and controlling its positioning screw, special care should be taken. If the transfer paper is placed on the tooth table for a long time, the residence time will be insufficient and the overprinting accuracy will be affected. The correct adjustment method is: twist the brake screw so that the roller on the rocker arm and the swinging cam of the paper feed roller are separated by a gap of about 0.08 mm. At this point, you should pay close attention to the position where the two sides are disengaged and enter the contact point (ensure that the transfer time of the transfer paper on the tooth table is 27°); the brakes on both sides should be at the same time, and leave at the same time, otherwise the paper transfer tooth is on the tooth table. When the upper paper is unstable, the paper is also inconsistent, and it is prone to longitudinal micro-overprinting. The above problem is mainly on the J2205 machine. This part of the PZ4880-01B four-color machine has only one brake on the inner side of the operation surface, and its positioning has disappeared because the paper transfer mechanism uses an equidistant conjugate cam and a cam. The design and processing precision has reached the requirement, so the brake only plays a protective role.
4. Water transfer roller, transfer roller shaft brake
When passing water and transferring ink, the brake should be in contact with the brake screw; when water is connected or ink is connected, under the action of the tension spring, there should be a gap between the two. It is easy to accumulate dirt such as ink and dust here. If it is not cleaned up in time, it will affect the active gap. It will cause difficulties in water supply and ink connection. It should be noted that it should be cleaned and refueled.
5. Embossing roller
The function and adjustment method are the same as those of the brake on the transfer shaft. It should be noted that after disassembling and repairing the boring shaft, the brake screw should be turned to open and close the dental bearing and the embossing on the boring shaft head. The distance between the shoulder and the shoulder iron is adjusted to 13±0.05mm. The clamps on the dental shaft must be loosened during calibration. After adjusting the position of the brake, adjust each tooth again.
6. Clutch pressure brake
The clutch pressure relies on the brake limit to prevent the pressure from being combined and the pressure from being excessive. The adjustment should be cautious. When adjusting, firstly press the brake screw and the pressure brake screw to the end; jog and press, when the maximum surface of the pressure cam contacts the roller, twist the brake lever to make it close to the brake. It is 0.08mm, and then depressurized; when the maximum surface of the pressure cam is in contact with the roller, adjust the pressure-biasing brake screw and the brake clearance to 0.02mm. Why is the pressure difference larger? This is because when the offset printing machine is operated, the pressing pressure is performed at a low speed, and the pressure is performed under high speed. The clutch shaft has a large inertia at high speed, so it is generally pressed against The clearance between the brake and the screw is slightly larger. The J2205 two-color machine has two sets of clutch pressures that are out of synch, that is, the upper group is slower than the first group, and the lower group is faster than one shot (relatively speaking), the second print of the first print is produced and the first color is not printed. .
This fault is mostly caused by improper clearance between the two sets of clutch press brakes and the brake screw. As long as the adjustment is careful, the fault will disappear.
7. Receiving teeth
The action of the delivery claw is the same as that of the delivery shaft.
During the operation of the offset printing machine, it is necessary to constantly observe whether the brakes are in the correct position, whether the brake screws are loose, and try to eliminate the fault in the bud.