There are actually a variety of strategies of applying rubber to a metal core in order to manufacture a roller. Get much more info about ลูกกลิ้งยาง
The most popular procedures are:
Wrapping a prepared calendared sheet of rubber about the core, that’s held amongst two points inside a lathe.
Extruding an endless rubber strip and applying it to a slowly rotating core that is definitely fixed amongst two points inside a spin station.
Sending the core by means of a cross head extruder, exactly where the rubber is flowing round the core, as a result covering it.
Putting the core involving the rolls of a Three-roll-builder and covering it with an endless calendared sheet of rubber – a roll of that is placed inside the Three-roll creating machine.
There are positive aspects and disadvantages to every of those procedures and particular circumstances exactly where one could be preferable to another.
- ‘Traditional’ wrapping
The ‘traditional’ wrapping starts with cutting the rubber sheet according to the demands of your roller (width and diameter) and placing the ready core in to the lathe. The core is turned gradually because the rubber sheet wraps around it.
Depending on the diameter essential and the geometry of the calendared sheets this wrapping must be repeated various instances. After reaching the final diameter (plus overbuild) a bandage might be wrapped around the roller within the same machine for curing purposes.
This method is low-priced and valid for rollers of a medium size each in length and diameter. It really is flexible and, given a roller of 1500 x 500 mm, requires roughly 15 minutes covering time which includes all setup and handling work.
Within the case of series production this method does not present any possibilities of price reduction. Additionally, it calls for calendared rubber sheets, which are much more high priced than rubber batches.
Care need to be taken as the connecting line among two rubber sheets plus the lack of pressure that sticks the rubber towards the core and itself, normally causes air bubbles. As a result of the relatively low investment required, this wrapping strategy is used in nearly each begin up company.
- Extrusion method
In comparison to regular wrapping, the strip extrusion method supplies several advantages. Firstly there is no should make use of the more high-priced calendared rubber; batches that may be fed towards the extruder are enough.
Secondly there is no limitation in the roller size. This method might be used for any roller width and diameter and it’s the only productive method to cover massive paper mill rollers.
Thirdly there is no set up time for different rollers as long as identical compounds are used; changing width and diameter do not affect the process at all.
What’s extra the compound remaining within the machine or reduce away at the ends in the roller following wrapping is often used once again with no more treatment.
It’s also attainable to decrease the wrapping time per roller by 10 to 20%, with staff preparing the next core though the process continues. And finally, the reject price is often cut down to about 50%.
You can find, nonetheless, some disadvantages. On account of the fact that the compound applied to the roller tends to flow to the ends, overbuilds of as much as 16 mm (around the diameter) is expected.
Important investment – up to ten times larger than for classic wrapping – and hugely skilled personnel are also essential. On average it requires a worker six to twelve months’ training to become a professional in extrusion.
Despite the improvement in rejects, you will find nonetheless two % or a lot more of rejects caused by air bubbles. Undoubtedly there’s a obtain in flexibility and cost reduction, but strip extrusion just isn’t the final solution in rubber roller covering.
- Cross head extrusion
For series production – starting with a great deal of 15 – 20 identical rollers and quantities in excess of one hundred rollers with identical compound – cross head extrusion is often a excellent alternative.
It also uses low-cost rubber batches and can lessen the covering time per roller (1000 mm wide) to about 2 minutes. Even when no less than two, typically 3, workers assistance the process, the personnel time per roller may be reduce down to 5 – 6 minutes, one third with the time required for the methods mentioned above.
While the benefits are clear, crosshead extrusion is just not a well-liked selection for roller companies. The main purpose will be the wide array of distinct rollers manufactured by the typical roller covering company in mixture with all the compact amount of identical rollers. You’ll find also diameter limitations with all the crosshead extruder.
Moreover these machines cost extra than £200.000 GBP and tiny or start-up companies can rarely afford such an investment. The skills necessary are also far beyond the typical understanding of roller covering. Even experienced companies meet new challenges with this approach from time to time.