acdii Report post Posted May 22, 2013 Still fuzzy math when you haven't used it for 20 years. I used to be able to calculate the blank dimensions needed based on a blue print using simple calculations, but that was 30 years ago and I have forgotten all that except that it uses the thickness of the material in the calculations. We did a comparison one day, my manager who taught me the method, vs this stuck up college prick who thought he knew everything. He did a complicated calculus calculation to come up with the blank dimensions, I used the method taught me. I was done in a few minutes while he was still working on one side. Numbers matched. I think the rule was something like, for each 90* bend subtract one material thickness from the overall dimension, for a fold over, twice the thickness, for a 45* 1/2 the thickness, or was it add it. Whichever one it was, for each bend you would take each measurement, like say a simple pan, with 1" bends, and its 12" across after the forming, made from .032" steel. 1" +12" + 1" + (.032*2) would give the blank dimensions. Like I said been 30 years, so I dont remember the full thing, but it was SO easy to do. I used to be able to do the same for gearing, but that required writing it all out. Quote Share this post Link to post Share on other sites
alpha754293 Report post Posted May 23, 2013 Still fuzzy math when you haven't used it for 20 years. I used to be able to calculate the blank dimensions needed based on a blue print using simple calculations, but that was 30 years ago and I have forgotten all that except that it uses the thickness of the material in the calculations. We did a comparison one day, my manager who taught me the method, vs this stuck up college prick who thought he knew everything. He did a complicated calculus calculation to come up with the blank dimensions, I used the method taught me. I was done in a few minutes while he was still working on one side. Numbers matched. I think the rule was something like, for each 90* bend subtract one material thickness from the overall dimension, for a fold over, twice the thickness, for a 45* 1/2 the thickness, or was it add it. Whichever one it was, for each bend you would take each measurement, like say a simple pan, with 1" bends, and its 12" across after the forming, made from .032" steel. 1" +12" + 1" + (.032*2) would give the blank dimensions. Like I said been 30 years, so I dont remember the full thing, but it was SO easy to do. I used to be able to do the same for gearing, but that required writing it all out. Two things: 1) I won't run through ALL of the math but if you know the diameter of your wheel&tire (combo), and you know the speed that you want to go at - you can figure out how fast your wheel has to turn in order to get there. (In engineering terms, usually the units would be in radians per second). But in "normal people" terms, it can be a variety of units (typically either wheel/axle rpm or degrees per second or degrees per minute.) If you know your final drive ratio - multiply a) (from above) with this to get what the input shaft of the diff needs to be. (Might be easier to visualize it has a rear wheel drive car even though you might not be driving one.) If you know your transmission ratio (for fixed gear ratios like regular transmissions - i.e. NOT CVTs), multiple b) (from the immediate above) and you should end up with the engine speed (input shaft of the transmission). That's the basic jist of it. The math itself is like...grade school math (so long as you can multiply two numbers with two decimal places together). But it's the physics that you gotta figure out what you need to do with the math. 2) I don't know if that many people actually do the blank size calculations by hand anymore. Some might and do so maybe if it's really super early in the program for the part, but the reality is nowadays, pretty much everything is done on the computer and I remember at my last company, our manufacturing guys in the engineering office above ours (in conjunction with the plant manufacturing engineers) would run all kinds of forming simulations. Parts are so complicated now - and while you can do blank sizing calculations with those rules of thumbs, if you have anything that ISN'T a 45 degree or 90 degree bend, you're kinda hosed. And the blank sizing also doesn't take into consideration the potential for folding or splitting/cracking of the sheet metal component during the stamping/forming operation. I remember seeing the sequencing chart for a stamped part and it's like a really long sheet of sheet steel so that it's almost like with each die operation, you're actually working on like forming 17 parts at the same time (each in its respective stage of the overall forming process). At least that's what it looks like and from the product engineer that I was working with, that's how he describe how the part is ACTUALLY made. (I never got a chance to visit the plant before I left the company - too busy doing stuff.) And then, you try to increase the material utilization, so depending on the part, you might try to make multiples of them at a time (multi-cavity tool). And you might even try to get other pieces from the same sheet (say like patch pieces from the center of circle cutouts that's stamped out to form a really big hole (like the opening for a coil spring on the spring link of a multi-link rear suspension system). And for complicated profiles, now you have laser cutting, water cutting, plasma cutting; if it's even more complicated than that, you have hydroforming. There's a LOT that goes on with sheet metal processing nowadays. And with the way things are going (at least for automotive manufacturing) - it's just going to get even more and more complicated. Quote Share this post Link to post Share on other sites
alpha754293 Report post Posted May 23, 2013 That also assumes that we don't abandon metals altogether for composites. ;) (At which point, said rule-of-thumb/back-of-the-envelop type calculations would just go right out the window. ;)) Quote Share this post Link to post Share on other sites
acdii Report post Posted May 23, 2013 Yep, then again, this WAS 30 years ago. I did use a computer for the turret punch press programming, which then created the program for the actual press itself by punching holes through a paper tape that you would feed into a reader on the machine. The company I worked for made the fan housings for Grainger. The press brakes were digital back stops, but manual pressure feed. No complicated press forming, just simple angles. We had two fed punch presses with progressive dies like you mentioned, but they were small ones. The complicated things I worked on were the lathe and bridgeport mill. I had made an adapter plate to fit a 1975 Chevy Vega 2 barrel Holly carb to a 1980 Toyota Corolla wagon out of a solid block of aluminum. Designed it, cut it, milled it, tapped it, made the throttle link adapters for it, and damn did that car run great. Quote Share this post Link to post Share on other sites
alpha754293 Report post Posted May 28, 2013 Yep, then again, this WAS 30 years ago. I did use a computer for the turret punch press programming, which then created the program for the actual press itself by punching holes through a paper tape that you would feed into a reader on the machine. The company I worked for made the fan housings for Grainger. The press brakes were digital back stops, but manual pressure feed. No complicated press forming, just simple angles. We had two fed punch presses with progressive dies like you mentioned, but they were small ones. The complicated things I worked on were the lathe and bridgeport mill. I had made an adapter plate to fit a 1975 Chevy Vega 2 barrel Holly carb to a 1980 Toyota Corolla wagon out of a solid block of aluminum. Designed it, cut it, milled it, tapped it, made the throttle link adapters for it, and damn did that car run great. I think some of the more complicated stuff that we had to do by hand was for our school's race car team where we'd glue sheets of pink foam together, which then was milled and prepped for carbon fibre layup. the most painful part (which admittedly, I never ACTUALLY did myself) was sanding that thing down until it was super smooth. Nowadays with things moving towards composites, or aluminum, or magnesium, or ultra-high strength steel, some of those forming "rules-of-thumb" probably might not apply at all, or nearly as readily. At my previous job, one of the projects I was helping out on was trying to figure out magnesium-to-magnesium joining methods and technologies and being able to characterize the joints and predict when they will fail. Fatigue and most other solid mechanics topics relating to steels is fairly well understood. Aluminum is getting better still. But magnesium is still a complete puzzle. Quote Share this post Link to post Share on other sites
acdii Report post Posted May 28, 2013 I love magnesium! Get it just right and it glows for a long time! :) During WWII the B-29 was notorious for lighting up the engines due to the magnesium content, but they finally figured out how to keep them cool enough not to light up. Quote Share this post Link to post Share on other sites
alpha754293 Report post Posted May 29, 2013 I love magnesium! Get it just right and it glows for a long time! :) During WWII the B-29 was notorious for lighting up the engines due to the magnesium content, but they finally figured out how to keep them cool enough not to light up. Yeah...one of the problems that magnesium-for-automotive faces right now is having an operator work on grinding or polishing magnesium parts and then working on ferrous metals. The magnesium dust can get on the clothing of the operator, and when they grind/polish say a steel part, the sparks from that is enough to ignite the magnesium dust on said clothing, which lights the guy on fire. But it's starting to make its way into the production automotive world now. 1 acdii reacted to this Quote Share this post Link to post Share on other sites
acdii Report post Posted May 29, 2013 Yeah...one of the problems that magnesium-for-automotive faces right now is having an operator work on grinding or polishing magnesium parts and then working on ferrous metals. The magnesium dust can get on the clothing of the operator, and when they grind/polish say a steel part, the sparks from that is enough to ignite the magnesium dust on said clothing, which lights the guy on fire. But it's starting to make its way into the production automotive world now.When I was younger, we made our own fireworks, and magnesium was one of the ingredients, and yep, we lit up some stuff by mistake. Have to be very careful around it, use plenty of lube when drilling it, or milling. It does make some pretty rockets though! Quote Share this post Link to post Share on other sites
kuzzi Report post Posted May 29, 2013 When I was younger, we made our own fireworks, and magnesium was one of the ingredients, and yep, we lit up some stuff by mistake. Have to be very careful around it, use plenty of lube when drilling it, or milling. It does make some pretty rockets though!Makes a good fuse for an Iron Thermite ignition, too. Lightweight and vibration resistant, magnesium is very useful. Quote Share this post Link to post Share on other sites
acdii Report post Posted May 29, 2013 Yeah, but NOTHING beats a little LOX on a Bar'b! Quote Share this post Link to post Share on other sites
alpha754293 Report post Posted May 29, 2013 When I was younger, we made our own fireworks, and magnesium was one of the ingredients, and yep, we lit up some stuff by mistake. Have to be very careful around it, use plenty of lube when drilling it, or milling. It does make some pretty rockets though! This whole 54.5 mpg CAFE fleet average is going to be VERY interesting. It is REALLY going to make making cars REALLY interesting in the coming years, and since weight and fuel are so closely related, and with Ford being such a global company now...as weird as this might sound - I am actually LOOKING FORWARD to those 1 AM conference calls to Asia. Quote Share this post Link to post Share on other sites
kuzzi Report post Posted May 29, 2013 On a safety related note, in the Volunteer Fire Department here, we are always struggling to keep up with the vehicle technology advancements in case we run into an incident involving these newer vehicles. Magnesium + water = no bueno Last night in training I went through my car showing the crew the battery disconnect and the location of the batteries and airbags. These new advances keep us on our feet in case we have to cut one of these up. There are SUVs out there with 50+ airbags (i.e. explosive devices when the jaws hit them), newer cars with back-bone center chassis (tougher to stabilize), light upper frames that could not support a pileup when using our vehicle stabilizing struts, and of course increasing use of magnesium (though not the "unstable" kind). That being said, I too am looking forward to the next innovations. Quote Share this post Link to post Share on other sites
alpha754293 Report post Posted May 30, 2013 On a safety related note, in the Volunteer Fire Department here, we are always struggling to keep up with the vehicle technology advancements in case we run into an incident involving these newer vehicles. Magnesium + water = no bueno Last night in training I went through my car showing the crew the battery disconnect and the location of the batteries and airbags. These new advances keep us on our feet in case we have to cut one of these up. There are SUVs out there with 50+ airbags (i.e. explosive devices when the jaws hit them), newer cars with back-bone center chassis (tougher to stabilize), light upper frames that could not support a pileup when using our vehicle stabilizing struts, and of course increasing use of magnesium (though not the "unstable" kind). That being said, I too am looking forward to the next innovations. It's almost like the first thing that first responders should do in the event of a motor vehicle accident now is disconnect ALL the batteries (even the 12V ones) so that it de-energizes the car so that hopefully there won't be any power going to the airbag charges. (And those suckers are POWERFUL, even the multi-stage ones.) Same thing with the high voltage batteries of pure EVs and (P)HEVs. And I would not be surprised if NHTSA is going to need to come up with a new certification crash test for battery systems for both front, small overlap, and side impacts to also test for intrusion of the battery into the occupant compartment and also whether the battery itself remains intact. (I was just told yesterday that part of my job now also involves reading the FMVSS, so I'm sure that I'll come across whether that has been added to the regulations/federal requirements soon enough. haha...it's a good thing that I love my job. Otherwise, I can't imagine anybody else saying that they would LOVE to read the FMVSS.) 2 dalesky and hybridbear reacted to this Quote Share this post Link to post Share on other sites
kuzzi Report post Posted May 30, 2013 That is our protocol to disconnect batteries, but there are some who get tunnel vision so bad that instead of disconnecting the batteries, they will cut through the wires instead. For a 12V, that's not a bad thing as sometimes the connections are corroded and the nuts are rounded and we just don't have the time. For the HVB, those orange cables are there as a warning NOT to cut. That's why I went through my car Tuesday to show them where the disconnect was. Another piece of hearsay that we get in the department is even when we do disconnect the 12V or HVB, there's a capacitor in the system somewhere that will store the energy and make the airbags go off if triggered. Any truth to that? 1 corncobs reacted to this Quote Share this post Link to post Share on other sites
dalesky Report post Posted May 30, 2013 (edited) I love magnesium! Get it just right and it glows for a long time! :) During WWII the B-29 was notorious for lighting up the engines due to the magnesium content, but they finally figured out how to keep them cool enough not to light up. I didn't realize that you were a WWII vet! Thanks for your service! (kidding, but not if you are a vet) I'm not quite that old myself, but served proudly in the Navy, where mileage be damned, it was full speed ahead!Have you visited the WWII memorial in DC? truly an amazing and inspiring place. I had the privilege to accompany some vets on an Honor Flight, and it was a very emotional and fulfilling experience.Now back to the topic, the A-10 Wart Hog planes frequently used depleted uranium armor piercing shells. Talk about lighting it up! To you Kuzzi, thanks for the info. I will keep it in mind if I ever see an accident with a hybrid, or God forbid if I am ever am in one. Edited May 30, 2013 by dalesky 1 acdii reacted to this Quote Share this post Link to post Share on other sites
alpha754293 Report post Posted May 30, 2013 That is our protocol to disconnect batteries, but there are some who get tunnel vision so bad that instead of disconnecting the batteries, they will cut through the wires instead. For a 12V, that's not a bad thing as sometimes the connections are corroded and the nuts are rounded and we just don't have the time. For the HVB, those orange cables are there as a warning NOT to cut. That's why I went through my car Tuesday to show them where the disconnect was. Another piece of hearsay that we get in the department is even when we do disconnect the 12V or HVB, there's a capacitor in the system somewhere that will store the energy and make the airbags go off if triggered. Any truth to that? So the beauty about my having gone to an engineering school like Kettering is that you end up meeting a LOT of engineers. I just sent a message over Facebook to a girl that I knew worked at one of the suppliers of airbags (she's an electrical engineer) and hopefully if she isn't able to answer that question, that she might have a name and contact of someone else that I would be able to ask. Otherwise, I would have to find out who our internal airbag person is (which then the information might be protected), so I'm trying the public road first. I didn't realize that you were a WWII vet! Thanks for your service! (kidding, but not if you are a vet) I'm not quite that old myself, but served proudly in the Navy, where mileage be damned, it was full speed ahead!Have you visited the WWII memorial in DC? truly an amazing and inspiring place. I had the privilege to accompany some vets on an Honor Flight, and it was a very emotional and fulfilling experience.Now back to the topic, the A-10 Wart Hog planes frequently used depleted uranium armor piercing shells. Talk about lighting it up! To you Kuzzi, thanks for the info. I will keep it in mind if I ever see an accident with a hybrid, or God forbid if I am ever am in one. Yea, let's hope that none of us here will be in an accident. But the first things that I would check for is to make sure that none of the occupants are injured, and more importantly, no head, neck, or back injuries (because those have the potential to REALLY REALLY bad). And then do a check for all other types of injuries. And then start securing the vehicle. Check for fluids (coolant, oil, fuel), and then disconnect all of the power sources. (That's what I would do, in that order.) And once the person is more or less secured, and the vehicle is secured, now to start with the occupant extraction. But yea, cars in the next 10 years is going to be quite different (from a first responder's perspective) compared to cars of today (and of course, compared to cars of years gone by). 1 kuzzi reacted to this Quote Share this post Link to post Share on other sites
acdii Report post Posted May 30, 2013 I didn't realize that you were a WWII vet! Thanks for your service! (kidding, but not if you are a vet) I'm not quite that old myself, but served proudly in the Navy, where mileage be damned, it was full speed ahead!Have you visited the WWII memorial in DC? truly an amazing and inspiring place. I had the privilege to accompany some vets on an Honor Flight, and it was a very emotional and fulfilling experience.Now back to the topic, the A-10 Wart Hog planes frequently used depleted uranium armor piercing shells. Talk about lighting it up! To you Kuzzi, thanks for the info. I will keep it in mind if I ever see an accident with a hybrid, or God forbid if I am ever am in one.Sorry not a Vet, I did join the Army when I was 18 but had a hardship discharge due to my father being sick. I got a full time job right after that so didn't pursue it when he passed. I did visit the WWII memorial right after it was opened, it was on our honeymoon. However, nothing ever had me so choked up as seeing the Wall. Seeing pictures of it doesnt do anything for you. Being up close and seeing all those names, if that doesnt make you cry, well, you really need a kick in the... Quote Share this post Link to post Share on other sites