Author Topic: Question about “heat treating” or “hardening” hot rolled A36 steel  (Read 7460 times)

Offline Ye-Ole Steam Dude

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Any thoughts as to adding some pre-hardened inserts (0-1, H-13, ETC.) On to the faces of your forming tool? These could be screwed & doweled/pinned on using flat ground stock.

 John

Hello John,

Most likely the only time that would really need a hard surface on the Punch is when I bend a round or hex piece of stock out of something like stainless. In cases like this what I have done in the past is use two pieces of stainless angle. I make up a set for the Press that they will be used on. For the Die, I machine a clean round corner on the outside edge that will sit in the "V" of the Die so as not to mark it. For the Punch piece, I also machine the outside edge but only enough to fit inside the Die piece. It is a bit awkward to hold the Punch piece in place until it makes contact with the part being bent, but it does work. I have used this same method on several Presses with good results.

On this new Press, most everything that I will be bending will be flat stock of aluminum or brass for a steam engine so not very likely to do any harm to the Punch or Die that I am making now.

Thank you for the suggestion and have a great day,
Thomas
Thomas

Offline Ye-Ole Steam Dude

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Hello everyone,

Got the first coat of primer on some of the parts even though there will be a little more welding needed on them.

Started the process of rough milling the Die which is a slow process with a lot of material to be removed. The Die blank is 2-inches wide by 1-3/4-inches high by 12-inches long and being held horizontal in the vise.

Next step was to set the Die blank at a 45 degree angle to do the final milling of the “V” opening. I used my Dial Indicator to establish an exact level position of the Die to the Mill table and used two c-clamps to hold everything in place prior to tack welding. Then I tacked welded the Die on each end to the angle iron to hold it in place while being milled. This assembly was then placed in the vise and the level re-checked with the Dial Indicator prior to any more milling. Now it is just a matter of removing the remaining material to form the “V” opening.

Have a great day,
Thomas
Thomas

Offline Mcgyver

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Started the process of rough milling the Die which is a slow process with a lot of material to be removed. The Die blank is 2-inches wide by 1-3/4-inches high by 12-inches long

That would be a large piece to quench, more than I would want to do.   You have to prepared for the material to move on a heat treatment which is why stuff is usually ground afterward.  Small solid shapes are more stable, but that longer shape carries some risk of moving about imo.  For brass and AL I'd skip heat treating, safer and no warping.  You'll bend a lot of material before wearing it appreciably and even if you did you can resurface.   If you are really worried about a wear, I'd make it out some prehardened chrome moly - tough and somewhat hard but still machinable

Second point, whats the angle in the bottom die?  it looks like 90.  Most of the time in a brake you're air bending and the bottom die has to be less than 90.  the material doesn't really contact the sides of the bottom die and you over bend to account for spring.  Maybe you're an experienced press hand and i'm telling the choir how to sing...but if not, it'll save you some pain.  With an air bend, much less force is required and afaik the most common approach, vs coining or bottom bending.  Bend radius is a function of material, bottom die width and top die radius.   You also need a radius at the top the V on the bottom die finished to very smooth surface - that's where material will get pulled over the die and that soft stuff will easily scratch

Incidentally you can fabricate a bottom die with round bar welde to the top of V block like shapes made of 1/2 plate every few inches.  We've done that to get special jobs done.   If you used tompson shafting or such you'd start with the bend surface hard and smooth.  Probably how i'd go at it.


EDIT, for what its worth the above is from experience with steel, I've only done AL and brass in a finger brake, so perhaps I'm not the best one to advise on AL/brass die design....but thats what works with steel
« Last Edit: October 08, 2018, 05:07:40 AM by Mcgyver »

Offline Ye-Ole Steam Dude

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Started the process of rough milling the Die which is a slow process with a lot of material to be removed. The Die blank is 2-inches wide by 1-3/4-inches high by 12-inches long

That would be a large piece to quench, more than I would want to do.   You have to prepared for the material to move on a heat treatment which is why stuff is usually ground afterward.  Small solid shapes are more stable, but that longer shape carries some risk of moving about imo.  For brass and AL I'd skip heat treating, safer and no warping.  You'll bend a lot of material before wearing it appreciably and even if you did you can resurface.   If you are really worried about a wear, I'd make it out some prehardened chrome moly - tough and somewhat hard but still machinable

Second point, whats the angle in the bottom die?  it looks like 90.  Most of the time in a brake you're air bending and the bottom die has to be less than 90.  the material doesn't really contact the sides of the bottom die and you over bend to account for spring.  Maybe you're an experienced press hand and i'm telling the choir how to sing...but if not, it'll save you some pain.  With an air bend, much less force is required and afaik the most common approach, vs coining or bottom bending.  Bend radius is a function of material, bottom die width and top die radius.   You also need a radius at the top the V on the bottom die finished to very smooth surface - that's where material will get pulled over the die and that soft stuff will easily scratch

Incidentally you can fabricate a bottom die with round bar welde to the top of V block like shapes made of 1/2 plate every few inches.  We've done that to get special jobs done.   If you used tompson shafting or such you'd start with the bend surface hard and smooth.  Probably how i'd go at it.


EDIT, for what its worth the above is from experience with steel, I've only done AL and brass in a finger brake, so perhaps I'm not the best one to advise on AL/brass die design....but thats what works with steel


Hello Mcgyver,

Thank you for this information. Over the years I have designed and built a number of Presses and I am using the term “Press” to define a vertical press that uses a Punch and Die. I have also owned and operated a number of commercially manufactured Presses. However I have never made from scratch either the Punch or Die and on this project I just wanted to make both parts rather than order them pre-made. I am now retired and this small Press will be used in my home hobby shop.

You are correct about the shape of the “V”, in as much it is a 90-degree. I designed the Die based on industry standards and the opening is 1-1/2-inches. Whereas the Punch is 1-inch thus making all the bends up to and including 1/4-inch thick material, requiring less force. The shoulders on the “V” will have a 1/4" radius when completed.

Here are two examples of bending a piece of material 4-inches wide, by 3/16-thick (.1875) and with a PSI yield of 33,000:

Force required to bend 90-degrees;
example #1   
1" Punch and a 1" Die = 6,379.81 pounds
example #2
1" Punch and a 1-1/2" Die = 4,120.88 pounds

I used the standard formula for the “perfect die opening” for this project, however I had to take into account that I cannot make a Die for every thickness of material that I will bend. Example, (based on my machine use) for 3/16-inch thick material the “perfect die width” would be 1.2860-inches. Knowing that the maximum thickness of material that I will every bend with this machine will be 1/4-inch, I elected to use the 1-1/2" V-width. The perfect die width for 1/4-inch is actually 1.7147-inches but I also took into account that over 95% of the material that I will be bending will be 3/16-inch or less and have a yield of less than 33,000 pounds. As you can understand, I had to make some compromise for this small Press.

Again, I do appreciate all your help and have a great day.
Thomas
Thomas

Offline Mcgyver

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Hi Thomas,

I was just playing with Cincinnati calculator (https://www.e-ci.com/press-brake-tonnage-load-calculator/)  and those tonnage calcs look a little light in comparison but I'm following what you saying.   The cinci calculator is for air bending and is close but a little higher than your numbers.  Bottom or coin bending will take 4x the force or more, so am I safe in assuming your numbers are based on an air bend?

What I was getting as is to get a 90 degree bend with air bending, you net to  bend past 90 (it springs back to 90) so the bottom die V opening is always less than 90 degrees.   

btw, the DIY bottom die I was trying to describe is sketched below.  Its a bit 'quick and dirty' compared to your design which is more solid and how commercial dies look, but it does make for a ready made smooth and hardening opening radius if you use hardened and ground shafting (thompson shafting).  Yours is tradition die shape and probably the right way to do it, just offering this up as an another approach.

Mike


Offline Ye-Ole Steam Dude

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Hi Thomas,

I was just playing with Cincinnati calculator (https://www.e-ci.com/press-brake-tonnage-load-calculator/)  and those tonnage calcs look a little light in comparison but I'm following what you saying.   The cinci calculator is for air bending and is close but a little higher than your numbers.  Bottom or coin bending will take 4x the force or more, so am I safe in assuming your numbers are based on an air bend?

What I was getting as is to get a 90 degree bend with air bending, you net to  bend past 90 (it springs back to 90) so the bottom die V opening is always less than 90 degrees.   

btw, the DIY bottom die I was trying to describe is sketched below.  Its a bit 'quick and dirty' compared to your design which is more solid and how commercial dies look, but it does make for a ready made smooth and hardening opening radius if you use hardened and ground shafting (thompson shafting).  Yours is tradition die shape and probably the right way to do it, just offering this up as an another approach.

Mike




Hey again Mike,

There are so many variables when it comes to "air bending" of any plates and there are a lot of differences in the calculations between a "Brake" and a "Press". If you would look at Wilson Punch and Die and their American Standard Dies under 4-inch, you will note that 90-degrees is the "standard". Almost all manufactures offer various degree of openings. The buyer's end use will dictate if a degree of greater or less is needed for their day to day application. My last Press was a 3-foot, 20-ton and I ordered an 85-degree opening for the Die because I was only bending 5052 Marine Grade aluminum.

You are very good at drawing to scale and the attached drawing looks really nice. Draw an end view of my Die to scale and also the Punch to scale. Then create several drawings using these subjects and use 1/16" thick in one, 1/8" in the second, 3/16" in the third and finally a 1/4" thick plate. Make the Punch go all the way to the bottom of the Die less the thickness of that subject and then note the angle of the bent material. You will see that using the same Punch and Die offer different results on each test subject. This is why I had stated that I had to make a compromise when I am only using one set of Punch and Dies. A fabricator in Nacogdoches that I used when I was still in business had a 250-ton 14-foot CNC Press ($350,000.00 cost) and they had almost equal that cost tied up in Punch and Die sets and that did not represent a full set.

For bending items for my little steam engines and several items for my Buggy project, I believe the Press that I am now making should do OK.

Again I truly appreciate your interest and suggestions and for following along. Hopefully I can complete the Press by next week sometime and we will see how it turns out.

I would guess that the leaves have already begun to change colors in your neck of the woods.
Have a great day,
Thomas
Thomas

Offline Mcgyver

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Please keep the pics coming.  I still cannot see you could get an air bend of 90 without the bottom die being less than 90, but you seem well in control so I look forward learning how it all comes together. 

There seem some slight differences in nomenclature, around here everyone it calls this a press brake and the dies are commonly called upper and lower, vs. die and punch.  I think you are more technically correct, I just mention it in case it created confusion; me using the local vernacular.

Here's a shot of my brakes, press and finger....big one at the plant and little I made in the garage. :)   If I had one, I like the small hydraulic press idea like you are making....much more capacity than the finger brake I made.  The big one is a 16' 300 ton cinci, I've used it but mostly the guys keep me away from it.....they have the impression that anyone from the office will surely destroy it if given half a chance :D

cheers








« Last Edit: October 08, 2018, 06:46:10 PM by Mcgyver »

Offline Ye-Ole Steam Dude

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Please keep the pics coming.  I still cannot see you could get an air bend of 90 without the bottom die being less than 90, but you seem well in control so I look forward learning how it all comes together. 

There seem some slight differences in nomenclature, around here everyone it calls this a press brake and the dies are commonly called upper and lower, vs. die and punch.  I think you are more technically correct, I just mention it in case it created confusion; me using the local vernacular.

Here's a shot of my brakes, press and finger....big one at the plant and little I made in the garage. :)   If I had one, I like the small hydraulic press idea like you are making....much more capacity than the finger brake I made.  The big one is a 16' 300 ton cinci, I've used it but mostly the guys keep me away from it.....they have the impression that anyone from the office will surely destroy it if given half a chance :D

cheers






Hello again Mike,

Originally (or a long time ago) a Press was like your big machine and a Brake was like your second machine. Actually your second machine was called a Pan Box Brake because it had individual "blades", "fingers" or "whatever" and this machine could form a Pan (as in a pan for water, etc.) or Box (as in a shoe box including a lid). All sheet metal shops had a Pan Box Brake. For whatever reason now days both pieces of equipment are called Press Brake? I am so old that it is hard for me to find an item in the Yellow Pages in a phone book...he he

You have done a beautiful job on the "Pan Box Brake", what size is it and what variation of blades/finger sizes are there.

I am attaching two photos of Presses that I built several years ago. The first one is a small 4-ton used mainly to bend stainless steel round rod. Note that the Punch is stationary and that the Die moves up toward the Punch. The second is a 3-foot by 20-ton Air over Hydraulic and is the one that I mentioned earlier.

Have a great day,
Thomas

PS, the 4-ton has a sticker Webee Mfg, which is a company that I use to own
Thomas

Offline Ye-Ole Steam Dude

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Hello everyone,

Finally after almost 3 days chewing on that hunk of steel, the Die is now completed. Making the “V” opening requires to remove almost 1/4 of the material in that bar.
Photo #1, showing inside of the “V” after milling is completed
Photo #2, I used a 1/8" ball end mill to mill a relief in the bottom center of the “V”
Photo #3, Punch and Die with a dollar bill to show size (penny no good here)
Photo #4, Inside view of the completed “V”
Photo #5, Assembly of the parts that are completed with the Punch and Die

This might seem like a lot of work, but this is the first time that I have made a Punch and a Die and it has been fun and a great learning experience. Neither one are perfect but I am very satisfied with the way they turned out.

Have a great day,
Thomas
Thomas

Offline bent

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Hmm.  All that work just to fold a dollar bill?  ;D

Offline Ye-Ole Steam Dude

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Hmm.  All that work just to fold a dollar bill?  ;D

OK if I am really lucky it will fold a five-dollar bill  :ShakeHead:

I am threading the guide rods now, so some assembly may start as early as tomorrow.

Have a great day,
Thomas
Thomas

Offline Ye-Ole Steam Dude

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Hello everyone,
   
Ugly as a mud fence right now with all the different colors and fresh welding soot but the Press is now assembled and working. I will take it all apart do a good cleaning and apply more primer and then apply the final coats of paint. While it is apart I might shorten the guide rods to close the “normal open” position by at least one-inch. Next photos will be when all the paint has dried.

Have a great day,
Thomas
Thomas

Offline crueby

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Looks great!
We'd each like one...!

Offline bent

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Dunno, I kind of like the multi-colored approach.  Keeps it easier when talking to the shop assistants - "hand me that thingamajig.  No, the purple one"

Offline Ye-Ole Steam Dude

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Looks great!
We'd each like one...!

Hello Chris,

I'm telling you, it is as handy as a pocket on a shirt, every shop really does need one.

Have a great day,
Thomas
Thomas

 

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