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Thin wall tube bending issues.

ronaldinho_07

Aluminum
Joined
May 23, 2016
Location
VietNam
I have a mandrel tube bender.
Machine's pressure was set at about 1200psi.

Titanium grade 2: 50mm OD,1mm wall thickness
Clr =1.5D
Mandrel ball diameter is about 47.5mm
Mandrel nose is forwarded about 1cm .
I have tried to bend ss 304 and having the same issues

Heavy wrinkles(buckles) inside radius.
And have hump outside radius,between mandrel ball.
Now mandrel is stuck inside the tube
Here is the picture.
Any help is greatly appreciated
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e373e7b03ec7ad69eba20f5fdc1dc68e.jpg

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Whetstone

Cast Iron
Joined
Mar 27, 2011
Location
Providence RI
Unfortunately I don't have much help to give as I have only just started to learn to use my mandrel bender and have zero formal training. Plus my requirements are not nearly as demanding. In my research I found the information from sites like Bend tooling to be very helpful. Here is one link to a bunch of setup formulas. Go through the technical information page to see more

http://www.bendtooling.com/bending_formulas.htm
 

ronaldinho_07

Aluminum
Joined
May 23, 2016
Location
VietNam
Moving mandrel back
803726a45069cc10d0cfef57f7d67547.jpg

Still have wrinkles
Then i increased pressure upto 1500 psi and this thing happened
950169b345fce1340b0477ec217d11de.jpg

ef75e1a25a7670851c1e1ec2f1dd4173.jpg

77f42510b01a57e889a9f0fbaff20c1d.jpg

I have one question:
If OD were 50mm ,bending die ID must be 50mm,right ?
My tube is 50mm now,but i check bending die ID is only 49mm

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Whetstone

Cast Iron
Joined
Mar 27, 2011
Location
Providence RI
Yes, I would think that dies would have to match, especially so with thin wall tube. I don't think upping the pressure (pressure die or clamp die?) is the way to go. From all the reading I have done minimal pressure is best.


1.5 d radius bending is about as demanding as it gets and you need a perfect setup to make it happen.
 

ronaldinho_07

Aluminum
Joined
May 23, 2016
Location
VietNam
Yes, I would think that dies would have to match, especially so with thin wall tube. I don't think upping the pressure (pressure die or clamp die?) is the way to go. From all the reading I have done minimal pressure is best.


1.5 d radius bending is about as demanding as it gets and you need a perfect setup to make it happen.
Thank Whetstone.
I have inspected my bend again.
Look like i need a closer pitch mandrel.
a608ddb0eb792c5550eddd0f9d4c56f9.jpg

d08e0115807cc40d46e3f7fad65df193.jpg

b49f3ce10f516892bdd70d0db7610b12.jpg


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Kiwi2wheels

Aluminum
Joined
Jan 12, 2008
Location
Orlando,FL, USA
I say this having used a lot of bends and having to clean the grease our before fabrication/welding; there seems to be no visible lubricant on your mandrel or in the tube.

While this is unlikely to be the cause of the problems you're having at present, it is something to consider when you get new tooling. Ti has a galling problem under the best of conditions.
 

adama

Diamond
Joined
Dec 28, 2004
Location
uk
You need lube, thats a bloody tight bend radius, do you have a larger radius tool you could try? ie a 2 or 2.5Clr? I only ever bend small steel tubes, sub 3/4" but i regularly bend down to 2Clr all be it at nothing like thoes wall to diameter ratios with out a manderal. When ever the tubes collapsing the thing to look for is tube slippage, seams to only need a slight amount to cause - make a massive reduction in bend quality. The score marks are bad, means the tubes not sliding like it should be either! Give the tooling a polish and make sure the tubes clean before attempting the bend.

I know the anneal states key for 304, no idea on the Ti front, but would assume its the same there too. Thats a really tight bend to form in thoes materials IMHO.

http://www.bendtooling.com is the best place i know for tube bending info online, if you can't solve it im sure they would be able to help - supply the tooling to do it if its possible in your grade of material (and it may well simply not be!)
 

ronaldinho_07

Aluminum
Joined
May 23, 2016
Location
VietNam
I did not have 2.5D clr rightnow
I have read some docs shows that i need 2D+ CLR for bending 1mm wt titanium unless i have ultrathin mandrel.
Because with 1mm wt,1.5D clr...i always see that material will flow into space between balls.

I will make 2.5D clr and update later
Thank you

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ronaldinho_07

Aluminum
Joined
May 23, 2016
Location
VietNam
looks like you need to anneal it first.

i have annealed it
update:
i have created a nose radius,after calculating,i put mandrel nose 8mm forward.
1100-1200 psi,the tube was broken when bending but i noticed that the tube was stuck between wiper-pressure die.it can not slip
if my tube were 50mm OD,how much groove diameter for pressure die and wiper ?
current is 50mm for both
 

cro-magnum

Plastic
Joined
Aug 31, 2010
Location
Phoenix
First Post here, I normally just look around on here. I have a background in Mandrel Tube Bending and it looks like you have the correct tools for the job but some things out of place. Before I go deep into specifics and spend a good deal of time helping to correct your situation. Please reply that you are still working on this and not just gone another direction on the project.

Please reply with some more data as well..

1. Have you found lube for ID of tube?

2. Is the pressure die (long strait block supporting the back of tube) hydraulic boost assist, on sliders, or locked in position. Pics always show it in a back position which would be making the tube drag by it. I don't know if this is for the picture or it does not move forward with the bend.

3. What is the OD of the bend tooling. I.E. 4" across the bend die makes for a 1D bend on 2" tubing.

4. The mandrel size sounds correct, but I do not like the links style. That link style is probably 20 years old and only allows for same plane bending. Perfect alignment to the bend plane is crucial.

5. Make sure the links are capable of the radius you are trying to produce. If they do not turn as tight as the bend die radius...game over.

6. What make and model is the Bend Machine
 

ronaldinho_07

Aluminum
Joined
May 23, 2016
Location
VietNam
Hello,i can bend my tube now,the pressure die has too much pressure on it,and tube is blocked and i also did some small adjustments on my mandrel.it is a bit oversize->blocked,tube can not" flow"

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shrisjk

Plastic
Joined
Jul 18, 2017
avoid Galling in bending of Ti material

I say this having used a lot of bends and having to clean the grease our before fabrication/welding; there seems to be no visible lubricant on your mandrel or in the tube.

While this is unlikely to be the cause of the problems you're having at present, it is something to consider when you get new tooling. Ti has a galling problem under the best of conditions.
.......................
Hi, Can you please help me with the possible solution to avoid Galling in bending of Ti material Tubes having 2D bend radius?
 

Kiwi2wheels

Aluminum
Joined
Jan 12, 2008
Location
Orlando,FL, USA
.......................
Hi, Can you please help me with the possible solution to avoid Galling in bending of Ti material Tubes having 2D bend radius?

I've never used a mandrel tube bender. All I could suggest is research a recommended lubricant for Ti mandrel bending. A MoS 2 based anti-seize ?
 








 
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