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radial bearings

  • Thread starter Thread starter Jeffcott
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Jeffcott

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Hello, studying weighing tapes I observed that some use of radial ball rollers, to a crown (skf 61900-2rs1) coupled on each side of the roller, I point out that the load is applied on the outer ring of the bearings. I was therefore wondering what the reason for such a choice was. I think it might be related to load problems but I also ask for your opinion.
 
This is probably the case because if you use only one bearing, sized to offer the required performance, it would cause an excessive radial footprint. two smaller bearings can support the same weight but with a lower outer diameter.
 
I agree with hunting on the reason, but in my opinion it is a type of assembly that is likely to lead to a wrong dimensioning: two coupled bearings never work by spraying the load identically, but there will always be one that works more than the other, because of the size of the guides that cannot be identical. iho would be more correct to switch to roller bearings to contain radial encumbrance, rather than to couple two ball bearings
 
I also share your zeigs opinion but my intention was only to try to understand a choice made by others. thanks also for your opinion!
 
Now I want to ask you two more questions:

1. why the axis inside the roller has an axial movement (equal to 1 mm)?

2. As in the case studied, I want to make rollers (cylinders) characterized by a diameter 30 mm, thickness 3 mm and minimum length of 320 mm being the tape 300 mm wide. the transported load will be equal to 5 kg and the bearings will be loaded on the outer radius. the axis must have a minimum diameter of 12 mm, I then chose skf bearings 61901 (or 61802 for a axis with diameter 15 mm).
What is at this point the most correct way to proceed with the sizing for bearing positioning?
 
hi! maybe the axis inside the roller possesses an axial movement to guarantee a possible thermal deformation of the rollers, the second question instead I do not happen
 
Jeffcott said:
Now I want to ask you two more questions:

1. why the axis inside the roller has an axial movement (equal to 1 mm)?

2. As in the case studied, I want to make rollers (cylinders) characterized by a diameter 30 mm, thickness 3 mm and minimum length of 320 mm being the tape 300 mm wide. the transported load will be equal to 5 kg and the bearings will be loaded on the outer radius. the axis must have a minimum diameter of 12 mm, I then chose skf bearings 61901 (or 61802 for a axis with diameter 15 mm).
What is at this point the most correct way to proceed with the sizing for bearing positioning?
Click to expand...
theoretical positioning is defined by js6/j6 tolerances for the tree and m6/m9 (memory wash) for the hub, however look at the tolerances that give you on the skf catalog. Axially it should be one locked and the other free.

the practical positioning you do is as follows:
- tolerances on the right hub in the catalogue or otherwise blocked
- tolerances on the h7 shaft on both bearings
- Axially leave a game equal to the thermal expansion that could undergo even if you usually hold 0.5 mm. If the upper one is likely to get the trees out of the inner ring of the bearing and make them work wrong... in fact you hear every so much clock)

there are however other flange bearing systems that are mounted with screws, a legero axial game and is all solved. :finger:
 
thank you very much for the mechanical responsemg, think that on another reel there is a game of 1.5 mm, cmq I will take into account how you wrote. :smile:
See you soon!
 
How do I know more about bearings? Is it enough to read the catalogue?
I care how to choose and how to mount, where is it written?
 
the catalog skf is a great start
is well done and there are many info inside
then... observe the existing mounts and so much experience!
experts non we are born, but we become. with commitment, constancy, abnegation!
 
So I need the catalogue? where can I find exerci or examples with dimensioning and reason of choice?
 
once a book, always of the skf, with examples of mounts... .
I don't know if they do it yet or if it's on the site.
 
thanks for the blown mbt but unfortunately nada and I am still in the high sea, plus I gave more than one look to the catalogs but I am able to choose and evaluate the mounting tolerances, I hope someone can help me
 
with a look it is difficult to solve problems
eventualmetne open a dedicated discussion, post a mounting scheme, loads etc. and we will find a solution
 
I took to begin the problem of a jeffcott discussion, the bearing is subject to a tangential force equal to 65 n due to the engine power, a radial one equal to 60 n each time the weight passes over the roller, the axis where place the bearing must be minimum 11 mm and the cylinder thickness with diameter 3 cm must be at least 3 mm. knowing all these measures I have to choose the bearing, how can I proceed? he also wrote that the speed must be 536 turns per minute. I took advantage of an example to better understand how to choose a bearing. I know that I have to respect the size but it is not clear to me the way of choice, can someone help me and explain the steps to do?
 
bearing subject to tangential force due to the motor??? ? explains. .
Besides, can you post a badge, a box?
 
on the skf catalog there is a paragraph relative the transmission with straps so I multiplied the shot for 1.3 I wrong? I do not understand however how such value is used cmq for the choice of the ciscinetto you begin with considering the limit load of fatigue? or what?
 
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