Hello - I desperately need help designing some sleeve bearings. I currently have to design and build 50 small presses. I have to be frugal with the design for the project to profitable. The presses will probably only run 6 months. A very simplified picture of the design and most of the design criteria is shown on the web page:
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. I've been wrestling with the design for a month because of the high loads and slow, oscillating type movement. I'm a mechanical engineer, but this application is about to beat me. Any help would be GREATLY appreciated. References to computer programs or text books would also be most helpful.
Without getting too deeply involved, I believe you require more area for the bushing. i.e. the .5 inch plate should be 1 inch or more at the bushing area. Generally, it is assumed that a 60 degree angle supports the load. (Some use the projected area.) With that you have about .5 sq. in. of area for your load which is very, very high. Much more than any bushings that I have used.
To keep your cost down, use a commercially available bushing. Two supplier companies that I have used for Self-Lubricating Bushings are:
Graphite Metallizing Corp., Yonkers, New York,
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Inc., Sykesville, Pennsylvania,
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Their engineering department can suggest a working material for your problem.
Why do you consider using some sort of rolling element bearings "over design" (per your link)? My SWAG is that rolling bearings (not necessarily _roller_ bearings) are going to be the cheapest way out by far.
I'd also be very concerned about the stress on the 3/4" shaft due to the combined shear, torsion and bending.
I agree that the 3/4" shaft is on the small side. I was initially designing the shaft using hardened 4140 material in the 40 - 45 Rc range, which is extremely strong and should easily meet the torsion/bending/shear needs. I have space limitations, but I can increase the shaft size.
What sort of roller element do you suggest? I've looked at needle bearings, but they can't handle the forces in the size range that I'm trying to meet. I'll consider anything at this point.
I'm really looking to make these presses as cheaply as possible. The combined cost of everything - including the many components that I haven't mentioned, is critical to it's success.
"I'm really looking to make these presses as cheaply as possible. The combined cost of everything - including the many components that I haven't mentioned, is critical to it's success."
You better be sure of your design, get yourself a good mechanical designer or protoytpe this thing & test it.
Otherwise you'll be looking at 50 units that don't work & need design mods to make them work. Keep in mind that it's easier to fix (or throw away) the prototype than fix 50 units.
remember.......... you can have it
fast, cheap or good.....pick two
if it's got to be cheap & good ..........take your time on the design & get it right
cheers Bob
PS here's a tip; just don't check strength / stresses....calc deflections as well
After a little thought, I'm going to back off on my previous reply. Have a look at spherical rod ends and spherical bearings. For example...
You may even be able to use rod ends in place of the vertical plates that are supporting the shaft. I'd consult the mfrs regarding load capacity under your loading conditions, but the *static* ratings exceed your load in the size range you're considering. A COM-16 1" bore bearing should run you around $25; rated static load is 55,200#.
Interesting idea, using rod end type bearings. I have to use the vertical plates because I'm mounting some components to them. However, I'm very intrigued by the load rating for the size. Do you know if they just sell the bearing part as a press in type device?
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