Turning large rubber rollers?

[ferrretcatcher]

I have customer with a process that wears away some larger rubber rollers. The rollers are about a foot diameter, 7 foot long and about 60 durometer. They get worn in the center and need resurfaced to maintain a consistent thickness across them. How and what is the best way to turn rubber? Would ideally like to maintain around 5 thou in size but not sure if its possible or not. Would a really sharp HSS tool or grinding somehow be best? Maybe even a hot knife like they groove tires with would possibly work? How about a flame treatment after turning to smooth them too? Lots of ideas but no practical solutions just yet. Any information is appreciated.

 

[BOB-OO]

No turning, grind them with a tool post grinder. Its very dirt, but effective and accurate. We do it in house for our coated rollers.

 

[Nmbmxer]

Look up tire shaving, it’s popular as part of balancing heavy truck tires and also used on racing tires to change the height of the tread. I don’t know what they use to grind the tire but the one I saw working on a truck tire was a smokey mess.

 

[Garwood]

The rubber roll building line I would have bought at auction for $300 if I was paying attention did it with large belt sanders.

 

[Bobnotthecat]

Sir,
We used to turn rubber rolls with a tool made from on old bearing race welded to a shank with a sharpened edge and heavy feeds. Finishing was done by grinding. If I remember correctly the grinding wheel was of very course grit.

Hoods and a vacuum are much desired for grinding though.

Bob....not the cat.

 

[boslab]

If I were to guess your refinishing extruder nip rolls ( they live at the top of a blown film extruder tower) just a guess from previous incarnations!
They usually get stuffed in a lathe and ground, like a toolpost grinder set up, though I used a big Churchill roll grinder with a 40 grit wheel, dirty job but simple.
I’ve not found a turning option that didn’t tear the surface unless it was damn near frozen solid.
Grinding was the best, I’ve seen one machine with basically a belt grinder on the carriage.
Mark

 

[hvnlymachining]

I've used a tool post grinder on urethane rollers with good success, sharp tools didn't finish as nice.

 

[eKretz]

You can cut rubber faster than grinding it but the finish is generally better done by grinding. To turn it you're going to want to broadnose. That is, use a razor sharp tool with a flat nose, aligned parallel to the work axis with the flat wider than your feedrate - which can be substantial. If you only have a little wear to remove, the grinder will probably do that.

 

[just Dave]

Don’t think little Dumore for serious grinding. Rubber takes HP. The best machine I‘ve seen in this roll was an OD grinder set up with a belt instead of wheel and coolant dust suppression. I have turned half inch a side off slitter saw rubbers with very steep relief on knife edge HSS and heavy feed.
You might be able to rig a HD hand held belt sander with dust collection as a tool post set up. Good luck

 

[BoxcarPete]

Yep, grind if you can. Otherwise you want to go at it with the sharpest tool you have, lots of rake, peeling a wide shallow chip like a skiving tool.

 

[M.B. Naegle]

I've never done the grinding thing, but if turning it, get it cold. Throw it in the freezer over night, or use dry ice to stiffen it up. Baby powder makes a good cutting lubricant and use sharp sharp HSS.

 

[eKretz]

I've never done the grinding thing, but if turning it, get it cold. Throw it in the freezer over night, or use dry ice to stiffen it up. Baby powder makes a good cutting lubricant and use sharp sharp HSS.

You have a bigger freezer than I do...

And not necessary if you use the proper tooling. If you try to run a plain regular single point tool, that would help. With a broadnose tool the rubber can't flex away past the width of the tool's flat nose. It has nowhere to go but off the roll.

 

[ratbldr427]

I have roughed them out with a carbide tip circular saw blade if they were real bad then finish with an induced porosity grinding wheel 46grit I think. Done with a Dumore TP grinder. The belt grinders look like the way to go but use what you got. Done 4"-8"x 60"L rolls. Not fast,nasty but got the job done.
I make some small 60mm polyurethane /aluminum wheels for our presses and the TP grinder and porous wheel is fast and adaquit in that application. I cover the roll with polyurethane tubing which doesn't require much grinding to true them.

 

[David_M]

Rubber Grinding Wheels and Tools


For fast roughing:

 

[richard newman]

This outfit has the above plus these:

Rubber Turning Tools - Rolmacon Global Ltd

rolmaconglobal.com

 

[BoxcarPete]

This outfit has the above plus these:

Rubber Turning Tools - Rolmacon Global Ltd

rolmaconglobal.com

That SW004 or something much like it is what I would use. Angle the cutting edge into the rubber to peel the flattest widest chip you can manage.

 

[MrWhoopee]

Belt grinder/sander mounted on the toolpost. Works better than a grinding wheel, doesn't tend to heat up or load up. Makes quite a mess, use a vacuum.

 

[Scottl]

It is possible to turn some rubber compounds using a shearing type tool, HSS as I recall. I haven't done it myself but saw it done. I don't know the exact shape of the tool because the particular old-time machinist blocked my view when I tried to look closely at it. Trade secret/job security.

 

[Peter from Holland]

I can agree with the belt grinder Very fast with a coarse grit like 80
Peter

 

[Scottl]

That SW004 or something much like it is what I would use. Angle the cutting edge into the rubber to peel the flattest widest chip you can manage.

That top one looks pretty much like what I saw from a distance before my view was blocked. I believe the edge was skewed left to right so it cut with somewhat of a slicing motion.