JPH0219336B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a device for preventing vibrations from occurring in the cylindrical portion of a hollow, thin-walled cylindrical body, such as a plate cylinder for a gravure printing machine, which is thin-walled, supported by end plates on both sides, and rotated at high speed during high-speed rotation.

[Conventional technology]

It is well known that when the plate cylinder of a gravure printing machine is rotated at high speed, vibrations occur on the surface of the cylindrical part, and this causes color misregistration in multicolor printing. Furthermore, when the surface of the cylindrical portion of the plate cylinder is polished, vibrations are generated on the surface, and it often happens that the surface of the cylindrical portion of the plate cylinder cannot be mirror-finished. On the other hand, there has been a demand for faster printing speeds, and the number of rotations of plate cylinders has already exceeded 500 times per minute. In addition, as speeds increase, the frequency of plate cylinder replacement tends to increase, and there is a desire to reduce the weight of plate cylinders in order to improve the efficiency of plate cylinder installation work. Rotational vibrations tend to occur more frequently due to attempts to make the wall thickness of the parts thinner and to change the material of the cylindrical part from cast iron to non-ferrous metals such as aluminum. As the mass of the thin cylindrical body decreases and the rotational speed increases in this way, the surface of the cylindrical body tends to generate minute vibrations with an amplitude of 1/10 mm or less. Therefore, conventionally, as illustrated in FIGS. 5 and 6, rubber rings 7 are laminated and inserted in the axial direction along the inner wall of the cylindrical portion 5a of the plate cylinder 5 to prevent the occurrence of vibration. has been completed.

[Problems to be solved by the invention]

By the way, in the conventional device, the size of the rubber ring 7 is also determined by the inner diameter dimension of the plate cylinder 5.
Therefore, each time the diameter of the plate cylinder 5 changes, a rubber ring 7 of a corresponding size is required, and various types of rubber rings 7 are required.
There was a problem that we had to keep it on hand. Further, there is also the drawback that the work of aligning and inserting a large number of rubber rings 7 into the plate cylinder 5 and removing them one by one consumes a considerable amount of time and effort. The reason why such work requires so much time and effort is that end plates 5b having holes 6 having a tapered pattern 5C are welded to both ends of the plate cylinder 5. This is because it is not easy to assemble or disassemble members within the cylinder. The present invention was made by focusing on the fact that all such conventional devices have problems in workability, and furthermore, it is difficult to make them adhere uniformly to the inner wall of a thin-walled cylindrical body over the entire width and circumference. It can be easily and quickly inserted into and removed from thin-walled cylindrical bodies, has good adhesion, and is versatile enough to be used for thin-walled cylindrical bodies with slightly different diameters. It is an object of the present invention to provide a novel device that makes it possible to prevent rotational vibrations at low cost and in a rational manner.

[Means to solve the problem]

Therefore, the present invention provides a thin-walled cylindrical body that is supported by end plates on both sides and rotated at high speed.
By inserting an airtight and flexible cylindrical air bag with an air valve attached to the end face, and filling the air bag with pressurized gas through the air valve, the cylindrical peripheral surface of the air bag is transferred to the thin cylindrical body. The structure is such that it is brought into close contact with the inner wall of the cylindrical portion. Further, it is also a preferable embodiment of the present invention that the air bag has a cylindrical portion in which thick portions and thin portions extending along the axis are alternately arranged in parallel, and the surface portion is uneven. Further, the thin wall portion is formed from a rubber-like elastic body, and the thick wall portion is formed from a rubber-like elastic body having a high specific gravity on the surface side of the rubber-like elastic body in the same layer as the thin wall portion. This is also a preferred embodiment.

[Effect]

The present invention having the above-mentioned structure is extremely easy to insert into a thin cylindrical body because the air bag, which has been deflated and deflated into a flat shape, can be inserted sequentially from the end. By connecting the air pipe and supplying pressurized gas for a short period of time, the air bag receives uniform internal pressure and adheres uniformly to the inner wall of the thin-walled rotating body. There is no risk of it happening. In addition, by configuring the cylindrical part of the airbag to have thick and thin parts arranged in parallel, the expansion action of the thin part ensures that the thick part is in close contact with the inner wall and is evenly distributed around the shaft. It can be brought into close contact and is effective in preventing vibrations. Furthermore, by using a rubber elastic body with a high specific gravity in the thick wall portion, it has excellent adhesion to the inner wall surface, and the damping property against vibrations due to the high weight is increased, so that the vibration isolation characteristics can be improved.

【Example】

Below, shaftless plate cylinders such as gravure printing machines

An embodiment showing a vibration prevention device for a [thin-walled rotating body] will be described in detail. The plate cylinder 5 generally has a cylindrical portion 5 as shown in FIG.
An end plate 5b having a hole 6 in the center with a tapered surface 5c is fixed by welding to both ends of a. This plate cylinder 5 is normally a clamping body that is moved back and forth by a handle or the like.

[Referred to as a push cup], a truncated cone-shaped clamping body having a tapered surface at an angle symmetrical to the tapered surface 5c is advanced in the axial direction, and printing is carried out with the plate cylinder 5 clamped from both sides. Assembled into the machine. After the air bag 1 is inserted into the inside of the plate cylinder 5 before assembly in this way, air pressure of about 2 kg/cm ² is sealed so that the outer circumferential surface of the cylindrical part 1a becomes the cylindrical part of the plate cylinder 5. The assembly is performed after making sure that it is in close contact with the inner wall of 5a. Therefore, the air bag 1 is connected to the cylindrical portion 5 of the plate cylinder 5.
The cylindrical part 5 has an outer diameter smaller than the inner diameter of a.
It has a cylindrical bag shape with a length smaller than the axial length L inside a, and the air valve 2 is fixed to one end surface or both end surfaces. This air valve 1 is made of a rubber-like elastic body, and can be obtained by the same manufacturing method as that used for vulcanizing air bags for automobile tire tubes or air spring rubber bellows, but materials such as natural rubber, neoprene rubber, butyl rubber, etc. are mentioned,
Butyl rubber is a preferable material because it has low air permeability and high airtightness. Depending on the size of the air bag, it may be formed into a bag having a thickness in the range of 1 to 10 mm, preferably 3 to 5 mm.As the diameter increases, the thickness naturally increases, but if necessary, It is also conceivable to manufacture the air bag from a reinforcing rubber sheet having a reinforcing cord as a core material, and this is also a preferred embodiment. The air bag 1 shown in the figure has an uneven surface and has semi-circular grooves extending along the axis at appropriate intervals, and the area where the semi-circular grooves are provided is used for injection of pressurized air. The plate cylinder 5 becomes a thin wall portion that expands, and the surface portions adjacent to both sides of the plate cylinder 5 form a thick wall portion that closely contacts the inner wall of the plate cylinder 5 and functions to increase mass. In addition to the example in which grooves are provided in this way, as in another example shown in FIGS.
A strip-shaped outer layer 4 made of a rubber-like elastic material with high specific gravity is divided equally around the outer circumference of the cylinder.

The air bag 1 is divided into 8 parts in the illustrated example], and is spaced apart so that only the rubber-like elastic body of the air bag 1 exists between the adjacent outer layers 4, 4, so that the thick and thin parts are separated. The structure may be such that the parts are arranged alternately in parallel around the cylinder axis. In this case as well, it goes without saying that the thin-walled portion becomes the portion that expands and contracts, and the thick-walled portion becomes the portion that comes into close contact with the inner wall of the plate cylinder 5 and functions to increase the mass. Furthermore, in addition to the above-mentioned examples, it is also possible to have round, diamond-shaped, rectangular, etc. concave portions or convex portions distributed in an appropriate arrangement. By the way, when rotating a thin cylindrical body at high speed,
Even if the accuracy of the rotational balance of the rotating cylindrical body is maintained, if the rotational speed increases, the body of the cylindrical body will

[Corresponding to the cylindrical portion 1a] tends to generate vibration due to resonance, and this phenomenon is observed when the cylindrical body is supported at both ends and the length of the cylindrical body is larger than the radius. . To avoid this resonance, the normal rotational speed n of the rotating body must be
It is necessary to maintain the relationship n/n _R ≧√2 between the rotational speed n _R and the resonance rotation speed n R , or to create a structure that can increase the vibration damping properties of the rotating cylindrical body. From this point of view, by bringing the rubber-like elastic body into close contact with the inside of the body 5a of the cylindrical body 5 using gas pressure, the mass difference between the metal part of the cylindrical body 5 and the rubber-like elastic body is utilized, and the entire body 5a is The purpose is to obtain damping properties. That is, an air bag 1 made of a rubber-like elastic body
is the cylindrical part 1 that is in close contact with the inside of the cylindrical part 5a of the cylindrical body.
Not only is a given a suitable thickness,
The cylindrical portion 5a of the rotating cylindrical body 5 has the cylindrical portion 1a in close contact with the cylindrical portion 1a by partially forming thick-walled portions with high specific gravity.
The mass of the vehicle increases, and the damping properties of the fuselage also increase. In addition, the air bags 1 inserted into each of the six plate cylinders 5 were filled with pressurized gas at a pressure of 2 kg/cm ² and it was confirmed that the circumferential surface of the cylindrical portion 1a was in close contact with the inner wall of each plate cylinder 5. The plate cylinder 5 rotates 500~
When six colors were printed at a speed of 600 times/minute, no printing color shift was found, thus proving that no microvibrations were generated. By the way, it takes about 2 minutes to insert the air bag 1 into the plate cylinder 5 and finish filling it with pressurized gas, and it also takes about 2 minutes to take it out. The time required for insertion and removal has been reduced to approximately 1/5. In addition, the surface polishing of the cylindrical portion 5a of the plate cylinder 5 is performed at a rotational speed.
As a result of testing at 900 rotations per minute, we were able to achieve a mirror finish that was close to a perfect circle, and it was confirmed that no slight vibrations were generated during rotation. In addition to plate cylinders, the thin-walled cylindrical bodies to which the present invention apparatus is applied include drums for copying machines, and if the present invention apparatus is used when polishing under high-speed rotation, the vibration-proofing effect will be great. A mirror finish can be achieved reliably.

【Effect of the invention】

As explained above, the present invention uses the airbag 1 as a vibration prevention member, so when inserting it into the thin-walled cylindrical body 5 and removing it from the outside, the airbag 1 must be compressed flat by removing the air inside it. If you go,
The operation of loading and unloading is extremely easy and can be done quickly, and the time and labor required for the work can be greatly reduced. In addition, by filling the air bag 1 with pressurized gas, the cylindrical circumferential surface of the air bag 1 can be uniformly and firmly adhered to the inner wall of the cylindrical portion 5a of the thin-walled cylindrical body 5 over the entire width and circumference. Since it can function to increase mass in a balanced state, vibrations during rotation can be effectively prevented. Furthermore, since the air bag 1 is used by expanding it with pressurized gas, there is an advantage that one type of air bag can be used for several types of thin cylinders having somewhat different diameters.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a printing press cylinder according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line A-A in FIG. 1, and FIG. 3 is a longitudinal sectional view of a printing press cylinder according to an embodiment of the present invention. A vertical cross-sectional view of the airbag, Figure 4 is B in Figure 3.
5 is a longitudinal sectional view showing a conventional vibration prevention device, and FIG. 6 is a sectional view taken along the line C--C in FIG. 5. 1...Airbag, 2...Airbarb, 4...
Outer layer, 5... Thin cylindrical body, 5a... Cylindrical part, 5b
...end plate.

Claims (1)

[Scope of Claims] 1. An air valve 2 is attached to the end face inside the cylindrical part 5a of the thin cylindrical body 5, which is supported by the end plates 5b on both sides and rotated at high speed, so that it has airtightness and flexibility. A cylindrical bag-shaped air bag 1 is inserted and pressurized gas is sealed in the air bag 1 through an air valve 2, so that the cylindrical peripheral surface of the air bag 1 is brought into close contact with the inner wall of the cylindrical portion 5a of the thin-walled cylindrical body 5. A rotation vibration prevention device for a thin-walled cylindrical body. 2 The air bag 1 has a cylindrical portion having thick portions and thin portions extending along the axis line and arranged alternately in parallel;
Claim 1, in which the surface portion has irregularities
A rotational vibration prevention device for a thin-walled cylindrical body as described in . 3 The air bag 1 is made of a rubber-like elastic material, and has an outer layer 4 made of a rubber-like elastic material of high specific gravity partially formed on the surface of the cylindrical portion by integral molding or adhesive molding to form the thick wall portion. A rotational vibration prevention device for a thin-walled cylindrical body according to claim 2.