Roller clutch press mode of lithographic printing machine - three-point suspension clutch pressure mechanism
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The type of clutch pressure mechanism. The clutch press mechanism is generally divided into two types: one is an eccentric sleeve type, and the other is a three-point suspension type.
Three-point suspension mechanism structure
The three-point suspension type clutch press adopts a three-point support roller, as shown in the figure: 1, 2 is an eccentric structure, 3 is a circular wheel plus a spring, 4 is a convex sleeve, and 5 is a shaft of a blanket cylinder, 6 It is a connecting rod. 1, 2 is a fixed point when the clutch pressure is applied. When the contact position of the convex sleeve and 1, 2 changes, the distance between the axis line of the blanket cylinder shaft 5 and 1, 2 changes, thereby realizing the clutch pressure. Let's analyze the role and working principle of these three points.
How does the three-point suspension mechanism work?
Point 1 is used to adjust the center distance of the drum, which is composed of an eccentric shaft and a bearing outer ring. When the position of the eccentric shaft changes, the position of the outer ring of the bearing also changes, and the axis of the drum also changes. The key to using the outer ring of the bearing is to change the sliding friction to rolling friction, reducing wear and power loss. The movement of this eccentric shaft is generally driven by the worm gear mechanism. In addition to this, there is another point of supporting the roller and bearing part of the printing pressure. Therefore, of the three points, 1 point is the thickest, and it is not allowed to break even if it fails.
Point 2 is used to position the boss 4, that is, each time the boss is in a new position, the point remains such that the boss does not continue to move to the right in the new position. Since this point only plays a positioning role, the required force is small, so its axis is relatively thin. For this reason, this point can also play a protective role. When the machine is subjected to a large impact, the point is a weak link, which is first broken to avoid further damage of other components. In addition to the above effects, another important role of this point is the voltage regulation. The structure of this point is basically the same as the structure of 1 point, and it is also an eccentric bearing plus a bearing outer ring. When the position of the eccentric shaft changes, the contact position of the boss 4 with the point changes, thereby changing the position of the drum and realizing the pressure regulation.
The movement of the eccentric shaft is generally driven by a gear, that is, the eccentric shaft is assembled with the shaft of the sector gear, and then the rotation of the sector gear is driven by a small gear. During normal operation, the gear does not rotate because the eccentric shaft itself is self-locking, that is, when the clutch is pressed.
Point 3 are used to reset the drum, even if the drum is stable at every new position. The 3-point structure consists of a strong spring plus a round wheel. When the boss 4 leaves the wheel, the spring is elongated to keep the wheel in contact with the boss, and the spring compresses when the boss pushes the wheel. Regardless of the change in the position of the convex sleeve, the 3 points are always in contact with the convex sleeve, so that the principle of the planar three-point positioning can always be satisfied, and the positioning relationship must be absolutely guaranteed. In addition to the above effects, the 3-point spring also has the function of buffering vibration, which makes the machine run more smoothly.
Analysis of advantages and disadvantages of three-point suspension mechanism
The three points are that the county floating clutch pressure mechanism has almost no requirements for the wall plate hole, which brings great convenience to the processing of the wall plate hole.
Less pressure regulation and high accuracy. And the adjustment is convenient. Because there are weak links with three points of support, it can effectively protect the machine.
However, the installation and commissioning of such a clutch press mechanism is troublesome, and it is necessary to use a dedicated tool and with sufficient experience to ensure the installation accuracy.
Since there are only three points of contact, the contact surface is relatively small, so the impact resistance is poor, and it is not suitable for large printing pressure. This is why the three-point suspension mechanism is widely used only on small offset printing equipment.
Compared with the eccentric clutch mechanism, the eccentric clutch pressure mechanism must be implemented by double eccentricity in order to consider the sequential clutch pressure. However, the eccentric mechanism is very complicated to process, and the machining accuracy is also very demanding. The clutch pressure is not required. In the mechanical structure to do more work to consider the sequential control, the electrical part is easy to achieve the function of the sequential clutch pressure.