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V1 of my hydraulic angle iron shear failed. Would appreciate any feedback so I can design a better V2.

Gotcha. I'll cancel the hard facing and add tool steel to the contact points.

A bit unclear on the spacing. Should I do the thickness of a sheet of paper, two sheets of paper?

Thanks
 
Gotcha. I'll cancel the hard facing and add tool steel to the contact points.

A bit unclear on the spacing. Should I do the thickness of a sheet of paper, two sheets of paper?

Thanks
Clearence is typically 7% of material thickness.
The cost to try building up the edge with hardfacing welding rod is way less than the cost of making and hardening tool steel edges. Also depends on how much use the thing will get.
 
Clearence is typically 7% of material thickness.
The cost to try building up the edge with hardfacing welding rod is way less than the cost of making and hardening tool steel edges. Also depends on how much use the thing will get.

Whelp fellas,

I removed the angle from the blade by cutting it flat, welded the frame to 1/2" plate so its more sturdy, and set a gap between the die and punch that is 7% of the material being shared (3/16" angle) and the die still can't cut through the workpiece.

I've wanted to try to build this for a very long time and am glad I did, just so I can stop thinking about it.

Learned a lot in the process and the new mindset will serve me for future projects.

Appreciate everyones help.
 

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Flip your channel so the V legs point down. This will mean that instead of punching throught the entire channel in one hit you are cutting a maximum length of (.707 x Material thickness)x2 if the punch is flat. Use a inverted V on your punch but make it shallow this will help balance the punch cutting forces and stop the punch drifting on the channel. If the V is to close to the angle of the channel you are increasing the cut length and hence the cutting force required. Fit a heel block behind your punch this will stop the punch deflecting. Use mild steel with a tool steel wear plate for the heel. Forget about hard welding the mild steel will just deflect under the weld or at worst the weld will just peel off. Thicken up the punch to give it more strength also make it wider if you use an inverted V as this weakens the punch.


You can use thick gauge plate strip for wear plates and cutting edges.
 
Flip your channel so the V legs point down. This will mean that instead of punching throught the entire channel in one hit you are cutting a maximum length of (.707 x Material thickness)x2 if the punch is flat. Use a inverted V on your punch but make it shallow this will help balance the punch cutting forces and stop the punch drifting on the channel. If the V is to close to the angle of the channel you are increasing the cut length and hence the cutting force required. Fit a heel block behind your punch this will stop the punch deflecting. Use mild steel with a tool steel wear plate for the heel. Forget about hard welding the mild steel will just deflect under the weld or at worst the weld will just peel off. Thicken up the punch to give it more strength also make it wider if you use an inverted V as this weakens the punch.


You can use thick gauge plate strip for wear plates and cutting edges.
It can't hurt to try. Thank you for the feedback.

I'll draft a 3D model tonight and post it here to get some feedback before I build it.
 
And add a hold down for the material to stop it lifting, this can just be a strap over the top that the material slides under. If the material starts to lift you are starting to go from shear to flange which is not good. If you need extra tonnage and you don't want to up the hydraulic cylinder then build a toggle to operate the punch they are incredibly powerful.
 
I appreciate you addressing every weak point of this design.

I welded the opposite end of the angle that is being cut to the angle bed frame to prevent lift, just to test the concept, before making a more permanent solution.

I built a pneumatic clamp that I was going to position over the angle to clamp it down, but am not yet sure if it is strong enough to hold it down. The cylinder bore is 1.5" and I'm running 90psi which will produce 159 pound force, or 707 newtons.

Here is a picture of it, do you think it might work as a clamp?
 

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Wouldn't bother with clamping like that unless you are continually changing thickness of material. A simple strap is fine on thicker material.
 
1/2” steel would make a hold down (they can just be a fixed bar about 1/16 over the material. Your air cylinder is not even close. more errthing.

125 ton angle shear frame:

image.jpgimage.jpg

65 ton frame:
image.jpgimage.jpgimage.jpgimage.jpg

Side load is exponentially more than shear load. You can see flex in the smaller machine when pushing it.

More, by a lot. Shears and punches are old school engineering machines.
Even paper scissors of decent quality have thick blades.
 
1/2” steel would make a hold down (they can just be a fixed bar about 1/16 over the material. Your air cylinder is not even close. more errthing.

125 ton angle shear frame:

View attachment 418695View attachment 418696

65 ton frame:
View attachment 418699View attachment 418697View attachment 418698View attachment 418699

Side load is exponentially more than shear load. You can see flex in the smaller machine when pushing it.

More, by a lot. Shears and punches are old school engineering machines.
Even paper scissors of decent quality have thick blades.

Oh, wow. Thank you for putting it into perspective.

I found a large press brake die that's 1" x 36" x 4" in my shop that I bought at an auction last year for $5. I was going to cut it up and try again since it's probably a better grade steel than mild steel, but now I'm not so sure it would work seeing your behemoth of a machine. I dunno, maybe I'll give it one last try and see what happens.

I looked quite a bit online and couldn't find what shear load and side load mean. Could you maybe explain that to me?
 
Flip your channel so the V legs point down. This will mean that instead of punching throught the entire channel in one hit you are cutting a maximum length of (.707 x Material thickness)x2 if the punch is flat. Use a inverted V on your punch but make it shallow this will help balance the punch cutting forces and stop the punch drifting on the channel. If the V is to close to the angle of the channel you are increasing the cut length and hence the cutting force required. Fit a heel block behind your punch this will stop the punch deflecting. Use mild steel with a tool steel wear plate for the heel. Forget about hard welding the mild steel will just deflect under the weld or at worst the weld will just peel off. Thicken up the punch to give it more strength also make it wider if you use an inverted V as this weakens the punch.


You can use thick gauge plate strip for wear plates and cutting edges.

Do you think this punch is shallow enough, or should i go wider?

Still working on the rest of the design, but figured I'd incorporate the die into the frame of the machine so it is more robust. Thoughts so far?
 

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Shallower angle on the punch. The way you have it the punch will be shearing all the way along the blade. You can even go flat but you will lose the self centring of the inverted V. Heel needs to be more robust.
 
OP - I think the double-shear idea you have in the model has merit, but that only works if you're cutting enough length to extend through the second die. I'd go for a robust stripper plate ("hold-down") and put the edge of that stripper plate exactly one hairsbreadth away from the edge of your die.

In cross section:
1701784321183.png




I believe the side-load that has been mentioned refers to the tendency of the punch to flex away from the line of cut (to the right in the schematic above). The double-shear will reduce this, as the loads are balanced. Unfortunately, if you only want to take a 1/4" thick nibble, the double shear doesn't help. Double shear will also require a lot of force.

Shear area: 1 1/2" angle @ 3/16" thick => 1.5" x .1875" x 2 legs = .5625 sq in. (yes, the legs overlap in that math, but that should account for the area of the inside fillet)

Ultimate Tensile Strength of structural steel (A36, first result on Google, higher end) = 75 ksi

Shear strength is ~1/3 of tensile => 25 ksi

Failure force = Stress * Area* number of shear planes = 25000psi * .5625 sq in. * 2 planes = about 14 tons.

I think the cylinder you spec'd was 40 tons, but that doesn't mean that everything else in the setup can handle 14 tons. Also, this is an idealized scenario of perfect shear (i.e., your die block and punch are hard as diamonds and have zero flexibility and they cut with zero tearing)

edit - had to put in picture of sketch
 
Shallower angle on the punch. The way you have it the punch will be shearing all the way along the blade. You can even go flat but you will lose the self centring of the inverted V. Heel needs to be more robust.


I found a large press break die in my shop that I bough a long time ago (won’t ever need it) and though about making the entire punch and die from it.

1. Do you think a punch entirely made of the press break die would be able to shear 2” angle with 3/16” walls, or should I buy some tool steel flat bar and machine inserts into the V ?

2. I looked quite a bit online and couldn’t find what the “heel” means. Is that the lowest part of the punch, that first comes in contact with the material being cut?

3. I’m thinking about welding the cyan and blue parts (guide walls and base plate) all together so the tool is stronger. Thoughts?

This is what I used for inspiration:

 

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OP - I think the double-shear idea you have in the model has merit, but that only works if you're cutting enough length to extend through the second die. I'd go for a robust stripper plate ("hold-down") and put the edge of that stripper plate exactly one hairsbreadth away from the edge of your die.

In cross section:
View attachment 418741




I believe the side-load that has been mentioned refers to the tendency of the punch to flex away from the line of cut (to the right in the schematic above). The double-shear will reduce this, as the loads are balanced. Unfortunately, if you only want to take a 1/4" thick nibble, the double shear doesn't help. Double shear will also require a lot of force.

Shear area: 1 1/2" angle @ 3/16" thick => 1.5" x .1875" x 2 legs = .5625 sq in. (yes, the legs overlap in that math, but that should account for the area of the inside fillet)

Ultimate Tensile Strength of structural steel (A36, first result on Google, higher end) = 75 ksi

Shear strength is ~1/3 of tensile => 25 ksi

Failure force = Stress * Area* number of shear planes = 25000psi * .5625 sq in. * 2 planes = about 14 tons.

I think the cylinder you spec'd was 40 tons, but that doesn't mean that everything else in the setup can handle 14 tons. Also, this is an idealized scenario of perfect shear (i.e., your die block and punch are hard as diamonds and have zero flexibility and they cut with zero tearing)

edit - had to put in picture of sketch


Thank you for the detailed explanation. I really appreciate it.

My power pack was set to 2,700psi but I bumped it to 3,500, which still isn't a lot compared to actual ironworkers, so I'll take it safe and design a flatter blade. Is this flat enough or should I go flatter on the punch?

My hoses are rated at 10,000psi, but the hydraulic cylinder will leak if I push it past 4,000psi. The cheap seals always leak. Wondering if I can get better seals to push it a bit more?

I definitely need to solve for stripper plate. What if I weld a 1” bar to the frame and have a screw to hold the workpiece down? Note, I made the screw end pointy in the 3D model, but it would be flat. Forgot I flipped the design upside down.

Thoughts?
 

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You only need a stripper if you are punching through something that closes around the punch when it is being retracted. The further from the trim edge the better, simple lever concept. However to far away and you can't cut small sections. Heel is the back side of the slot you have the punch pushing against. Whatever you do don't try cut off slivers of material as the material will flow between the punch and die and jam everything. You can grind an angle onto the blades which aids cutting however you then can't flip them before regrind.
 








 
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