Dimensional tolerance of anilox roller (top)

Dimensional tolerance is a key factor affecting the performance of the anilox roller.

Most articles and technical literature on anilox rolls fall into the following four areas:

1. Engraving (geometric shape, number of screen lines, ratio of depth to opening angle, etc.);

2.2 Laser (pulse CO2, continuous wave CO2 and YAG);

3. Coating of ceramic surface;

4. Cleaning, care and maintenance.

These problems are very important, and they need in-depth research and understanding to develop an ideal anilox roller system to ensure the stability of printing quality. However, to make these important parts work properly, printers and anilox roll suppliers should also pay attention to other aspects. This article is a brief introduction to some basic knowledge of the dimensional tolerance of the anilox roller, including: bearings, bearing surfaces, gears, balance.

The size tolerance of the anilox roller is important because if the dimensional stability cannot be maintained, then no matter what the geometry of the mesh is, the number of screen lines or the depth and opening of the engraving, what kind of use Laser engraving, how good is the quality of the anilox roller, or how well the anilox roller is cleaned, maintained, and maintained, can not get satisfactory prints.

All the components of the anilox roller, such as the diameter of the bearing surface, the diameter of the gears of each stage, the keyway, balance, TIR (total indication deviation), the characteristics of the cylinder, the ring, and the diameter of the engraved surface must fall in Within the determined tolerance range, otherwise the anilox roller will not operate normally. These problems are often overlooked, or the impact of tolerances on quality cannot be fully understood. Let's take a look at the issues related to space dimensions and tolerances.

1. Bearing and bearing surface

The diameter of the bearing surface must meet the tolerance range specified by the bearing manufacturer. Different bearing types and installation requirements have corresponding changes in parameters. Different bearings are different in inner diameter, outer diameter, allowable deviation, rated load, etc. The deviation range of a bearing tolerance refers to the centrifugal situation of the bearing deviating from its absolute central axis. There are many ways to describe this deviation, and we will explain it later.

At present, many printers do not have the structural drawings of the printing machine, and they do not know the tolerance or tolerance of the outer diameter of the bearing surface of the anilox roller. Some people may not believe it, but it is true. The easiest way to understand these basic parameters is to turn to the printer manufacturer. Another way to understand the size of the bearing surface is to find the name of the bearing manufacturer. Usually the name is always engraved on the bearing base and written with the bearing number. After finding it, call the bearing supplier for specific parameter data. The following table lists the diameter tolerance of a brand flange mounted bearing, which can be used as a reference.

Bearing sleeve tolerance

0.5 inches—1.937 inches, +0.0000 inches to -0.0005 inches

2 inches-3 inches, +0.0000 inches to -0.0010 inches

3.187 inches or more, +0.0000 inches to -0.0015 inches

Bearing inner diameter tolerance

0.5 inches-0.625 inches, +0.0008 inches to -0.0000 inches

0.75 inches—1.937 inches, +0.0009 inches to -0.0000 inches

2 inches-3 inches, +0.0010 inches to -0.0000 inches

3—3.187 inches or more, +0.0012 inches to -0.0000 inches

Taking the above table as an example, if a bearing with an inner diameter of 0.5 inches, the possible tolerance of the bearing surface (that is, the bearing sleeve tolerance) is: the maximum diameter is 0.5 inches, and the minimum diameter is 0.4995 inches. The bushings at both ends of the anilox roll are also commonly referred to as "shaft journals".

If the size of the bearing surface is too small, it will cause the drum to rattle and cause inaccurate positioning, which will reduce the service life of the bearing and damage the bearing surface. A poorly maintained bearing will become hard during continuous operation, causing severe wear on the bearing sleeve surface. In severe cases, a new bearing sleeve needs to be replaced.

Maintenance personnel who unload old bearings or install new bearings must ensure that the bearing surface and the bearing itself have not been damaged too much. Frequent shaft sleeve damages include obvious groove marks, gaps, grooves, or scratches on the drum surface caused by hammers, screwdrivers, rods, and any other tools that may be used during the unloading of bearings.

A basic principle is: the bearing must not be knocked on or under the shaft. Improper handling of bearings during bearing installation will cause the bushing to bend, resulting in excessive TIR (total indicated runout), which can cause multiple printing failures and reduce bearing life. For anilox rollers, TIR refers to how the drum body (engraving area) and the bearing sleeve on the roller shaft work together. In general, the TIR of a bearing sleeve should not exceed 0.0005 inches.

It is best to invest in a better bearing disassembly tool (the bearing is pulled out) to unload the bearing, and strictly follow the manufacturer's operating recommendations during the installation process. Before installing the bearing, a bearing heater can be used to expand the bearing base, and after contraction, the bearing and the base can be perfectly matched. When installing the internal bearing, it is best to place the bearing in a cooler to cool for an hour, allow the bearing to shrink to fit smoothly into the inner hole, and seal the bearing when it returns to ambient temperature. In addition to this, it must also ensure that the bearing surface is free of spots or rough burrs. It is also necessary to ensure that the bearing bore used in the outer diameter assembly or the bearing bore used in the inner hole assembly is clean. A good suggestion is to apply a very thin film of oil on the surface that is not very smooth before installation. The smaller bearing surface radius or the inclined surface of the bearing bore can also make the installation process easier. If the bearing is not installed correctly, the bearing will be damaged and the surface of the bearing or the surface of the inner hole will be offset. The result is that these surfaces cannot be concentric or the size is incorrect. These conditions may affect the future installation and cause TIR failure. Eventually affect the printing quality and increase the additional cost of cylinder repair.

Usually in printing applications, "standard size" bearings are installed on a machine that runs and slides. Installing bearings on such machines does not require pressure or other forms of force. Such bearings are commonly used on high-precision machines, calipers, high-friction machinery and other moving machine parts.

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