|
|
I have always put the arch back in flatbed trailers by shrinking the lower flange with a big rosebud. I know how it works. when you quickly heat the metal, it tries to expand but has no place to go, so it increases in section, then when it cools, It contracts and makes one flange of the beam shorter creating an arch.It is a bit of an art because you have to know what color to get the metal, and how far apart to space your heated areas to get the arch that you want.I have never had a problem with using this method to camber beams.But now and again I get someone who is supposed to know what they are talking about who claims that that method is no good and half azzed. They claim have to use big hydraulic presses and all kinds of crazy poop to do it right.I am always thinking WTF? And then concluding they are full of poop.I don't know, but I have cambered some seriously large beams for all kinds applications using a rosebud and some skill. In fact I have never seen it done any other way.The only other thing I have done to get a camber is fabricate the beams using a web that is cut in a crescent shape on out of a piece of plate.What I am asking is, Can i tell them they are full of poop in good conscience?Joewww.CummingsHauling.com
Reply:I do the same thing, Joe, heat-shrinking the lower flange to arch trailers, and you are right, it is an art more than a science. Also works in straightening I-beams and H-beams. However, many of the large trailer manufacturers and trailer shops today do it with presses, which is more of a science than an art. Easier, faster, and if you do enough of them, cheaper.
Reply:I always wondered how they got that arch in there.
Reply:What I am asking is, Can i tell them they are full of poop in good conscience?
Reply:Originally Posted by tanky321I always wondered how they got that arch in there.
Reply:Heat..Same process to straighten shafts in a lathe.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:I have always said "give me a big enough piece of steel and enough heat, and I could move the world". It is in the natural properties of steel to contract on cooling more than it expanded when heated to a certain point, that is why you get the arch when only one side is heated. If you heat a small section of steel and watch it very closely, you will see it first expand from the heat, then when it begins cooling, it will shrink past where it was before heating. This is not aimed at you experienced guys. I'm sure you know this.SA200,Ranger8,Trailblazer251NT,MM250,Dayton225AC,T D-XL75,SpoolMate3545SGA100C,HF-15-1 RFCS-14 When I stick it, it stays stuck!
Reply:Originally Posted by joethemechanicI have always put the arch back in flatbed trailers by shrinking the lower flange with a big rosebud. I know how it works. when you quickly heat the metal, it tries to expand but has no place to go, so it increases in section, then when it cools, It contracts and makes one flange of the beam shorter creating an arch.It is a bit of an art because you have to know what color to get the metal, and how far apart to space your heated areas to get the arch that you want.I have never had a problem with using this method to camber beams.But now and again I get someone who is supposed to know what they are talking about who claims that that method is no good and half azzed. They claim have to use big hydraulic presses and all kinds of crazy poop to do it right.I am always thinking WTF? And then concluding they are full of poop.I don't know, but I have cambered some seriously large beams for all kinds applications using a rosebud and some skill. In fact I have never seen it done any other way.The only other thing I have done to get a camber is fabricate the beams using a web that is cut in a crescent shape on out of a piece of plate.What I am asking is, Can i tell them they are full of poop in good conscience?
Reply:I used to put all kinds of radii on structural tubes with heat. There was no one around who could mechanically roll these tubes to the required radii so heat was the only option. If you don't know what you are doing, and really heat the piss out of it, you can compromise the mechanical properties of the material.
Reply:Originally Posted by zapsterHeat..Same process to straighten shafts in a lathe.....zap!
Reply:Originally Posted by tortisok, i give. how do you straighten a shaft with heat?
Reply:Great Dane trailers in Savannah GA uses hydraulics to camber their trailers. the ends of the beams are clamped down and a huge arm moves back and forth increasing the pressure on every pass. they are usually done in sets of two's. the clamps even change angles as the camber is laid in. they make their beams from a piece 7ga 55" wide and the length can be all the way up to 53'. the single sheet is pressed to form the beam and seam welded with a computer ran mig. it's a neat process to watch. it takes 7 or 10 mins to camber the set of beams where they are sent to the welding area and assembled and welded by folks like us.Sentry trailers in florence SC uses straight beams for the types of trailers they build. but the jig they use is warped like 3/16". their welders weld all the trailers in a certain order at preselected amps (engineers decide) and when the trailer cools it literally pulls itself straight. too much math involved i believe for all that, but it works for them.the steel plant i worked for supplied materials to both of these companies. anytime they had QC issues it was mine and my bosses job to go to there facilities and smooth things over, or prove the material is fine and their operators are effed up. but here at the home-20 it's heat or my vice and 36" pipe wrench."Retreat hell, were just fighting in the other direction"Miller Trailblazer 302, Extreme 12 VS, Dimension 400, Spectrum 375, HF 251D-1, Milermatic 251 w/ spoolgun Hypertherm 1000Lincoln sp 1702000 F-450 to haul it
Reply:while heat shrinking is undoubtably an art, there is quite a bit of science behind it...http://books.google.com/books?id=UT5...BT9E#PPA128,M1
Reply:Not really my cup of tea, but I know that some beams have the arch rolled into it. An older friend of mine who owns a large tool and die machine shop around here (now semi-retired) has built rollers for this very thing. Who they were for I don't know, but I saw them building them, and wished I had gotten some pics of it. It was quite a roller.I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:I have no doubt that there are places that roll beams to put a camber in them. But those places are into production work. But in the repair business as far as I know it has always been done with a rosebud and a good eye.I just get sick of the comments from the peanut gallery. The average person thinks everything is done by specialized computer controlled equipment by special guys in special uniforms who live in special boxes.Seems like they are more apt to believe bull**** that the truth.Joewww.CummingsHauling.com
Reply:The shop I just left built locomotive frames among other things, they made about one a week. They cambered the two beams that ran the length of the chassis with heat.Yup
Reply:I am about to camber a W30"x235#X45'. need only 3/4" total camber.
Reply:Originally Posted by Fat BastardI am about to camber a W30"x235#X45'. need only 3/4" total camber.
Reply:3/4" over 45' is nothing....I've seen factory straight stuff with more camber than that....you could probably drop it on a couple of blocks and get that much in it, cold......
Reply:That is what I thought...Well we heated up the flange over a 2'area to 1000F and letting it cool I got camber but the wrong direction.The side I heated is up 1 1/4" WTF. (the flange that is up is the one I heated) Attached Images
Reply:Anyone doing the heat method, feel free to post pics so the curious can get an idea of what regions to heat.
Reply:FB, I'm sure that you had the ends blocked up?We used to straighten skids for gas and oil separator packages that got warped during welding with a rose bud.Leo
Reply:Shrinking beams to camber is slow and labor intensive. The big caveat now is that the new structural alloys are strain hardened when rolled to increase ultimate tensile strength. If you heat these alloys the grain structure changes and the strength is decreased. As these alloys become more common we will have to camber beams cold by force. Many large shops camber using a press since it is much faster.I will look around form some pics in my files and post.
Reply:Ok here is an an example from many years ago. The pieces were delivered with the camber that was not wanted. They were delivered to the sign shop bent and of course they sent them to us to work our black magic on them. The two tees were to become uprights that would support a large sign. I don't have a picture but I clamped them back to back by the flanges in the center then drove wedges in the ends to increase the force and help the shrinkage. Attached Images
Reply:Neat trick. Thanks for the pics.Anybody that would argue that there is only one way to accomplish a task is either ignorant or a lot smarter than any one I have ever heard of.I offer three choices: Good, Fast, & Cheap. You may pick two.Hobart AC/DC StikMate LXHarbor Freight AD HoodHarbor Freight Industrial Chop SawDeVilbis 20 Gallon, 5 HP Compressor
Reply:Shop I used to be in would roll them through a press - basically just a series of opposed wheels, had to have a sharp operator to keep from running them all the way out and sending them out the side of the shop.For the heavier beams it was all hydraulic press to meet desired camber - heat to cure factory unwanted factory FUBAR(nothing brightens your day like seeing a 72' long W24x670 land on your saw line - looking like a rainbow, touching TWO rollers)
Reply:Hi we do it every day they build camber machines Peddinghouse and Camco but NYS will not allow flame camber only 1100 F max thee are books from USS and Bethlehem on it you lay out triangles on the web on a spacing and use Ox Fuel rosebuds on them , best are Harris tips . light beams we do with a squirtmobile tractor holding a Harris 3-H tip on the outside flange at the web centerline not to distort the web. beam is flat on skids ,checked with a string and ruler. Our trailer builder has fixed bent 50 ton single drops the same way and put camber in them with all crossmembers in them with only one torch. You can cold bend using jacks , press brakes , steel bulldozers .,etc they all work.
Reply:The drawing for bending the beam the strong way is a little radical. Don't need to take that big of a bite on the flange. Attached ImagesDont pay any attention to meIm just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:OK so I've got a 30' w12x45 beam I got to put a 1/2' camber in. Yeah I know this doesn't seem like much but it's prooving to be harder than it sounds. I'm sure I'm just going at it the wrong way. I tried heating just the center in 12" sections in various spots along the beam with not much luck. Then I tried just walking down the beam heating the center (not too hot) the whole length, it seemed to make a little more progress. My main concerns is how much the beam will spring back once I take the tension off. I need a 1/2" camber, so should I go a inch? The chains and binders I have on it are tighter than a frogs hair stretched over a knats a** right now. I'm hoping I'll get lucky and get a response right away, otherwise I might be done with it by the time I post next. Thanks.Last edited by WelderDude; 11-22-2011 at 07:02 PM.
Reply:What you have to do is shrink the beam in a pie section. Heat the center of the web like you did for about six inches then go underneath and heat the web in a V shape reaching past the midline of the beam. Go back on top and get that red at the same time.When you heat the web area alternate sides so that the red heat is through the thickness. I avoid heating the edges of the web because it is so easy to accidentally pull the beam sidways and put a sweep in it. Do one heat like that a foot from your post then cool it down with wet rags. Apply the wet rags on the black areas working your way to the center of the red. Do not apply directly on the red areas. You want the red so that it upsets and the cooling forces the shrinkage. You can run a string end to end and check camber. Once you have seen what one heat will do then you can figure roughly how many more are needed. You have shrunk it slightly but the web and the flange is too much for the shinkage stress you put in the centerline of the web so nothing moved.I worked in a shop that had imbeds in the concrete floor. We had to shrink 200 pound per foot beams. I got the bright idea like you are doing only I tacked a lug to the imbed and used a chain comalong to pull down. You think yours was tight eh?? I accidentally pull the imbed out of the concrete floor about half an inch. I am retired now so can laugh at my follies twenty years ago.Last edited by lotechman; 11-22-2011 at 08:13 PM.
Reply:Originally Posted by lotechmanWhat you have to do is shrink the beam in a pie section. Heat the center of the web like you did for about six inches then go underneath and heat the web in a V shape reaching past the midline of the beam. Go back on top and get that red at the same time.When you heat the web area alternate sides so that the red heat is through the thickness. I avoid heating the edges of the web because it is so easy to accidentally pull the beam sidways and put a sweep in it. Do one heat like that a foot from your post then cool it down with wet rags. Apply the wet rags on the black areas working your way to the center of the red. Do not apply directly on the red areas. You want the red so that it upsets and the cooling forces the shrinkage. You can run a string end to end and check camber. Once you have seen what one heat will do then you can figure roughly how many more are needed. You have shrunk it slightly but the web and the flange is too much for the shinkage stress you put in the centerline of the web so nothing moved.I worked in a shop that had imbeds in the concrete floor. We had to shrink 200 pound per foot beams. I got the bright idea like you are doing only I tacked a lug to the imbed and used a chain comalong to pull down. You think yours was tight eh?? I accidentally pull the imbed out of the concrete floor about half an inch. I am retired now so can laugh at my follies twenty years ago.
Reply:Do it like the first picture but a narrow Vee and you can ignore heating the complete flange across because of the risk of accidental sweeping. The reason you can ignore is that when the flange is rolled out at the mill there usually shrinkage stresses in the edges of the web already. Keep in mind that as engineering specs get tighter heat shrinking beams is starting to be banned and the beams have to be bent by hydraulics. Most imaginitive rig I saw was a huge frame and hydraulic cylinder out of a ore truck set horizontally. To drive the hydraulics the shop added a set of quick disconnects to the forklift. They could park the forklift beside and used its hydraulics. When they were finished they parked the frame out back.
Reply:No, you cannot tell them they are "full of poop". I mean, you can, but you would look pretty ignorant. Service centers (the places some shops buy steel from) offer a variety of services including cambering (also sand blasting, cutting, etc.). These places use gag presses to induce camber. While heating has its place gag presses are far more economical when doing any sort of volume. We have been known to use heat in a pinch, and it's basically a must in the situation you described - repair.
Reply:Thats a pretty heavy beam to camber by centerline heating, some wedges, or maybe even just heating across the flange every couple of feet would probably be pretty good
Reply:Cambering a beam can be done with a rolling machine as well. Our capacity is as follows:• Cambering of wide flange beams, max 10" & 20 ls/ftCost is between .30 - .50 per pound. A decision can than be made whether it is worth the cost to have it cambered by an outside party to free up additional fabrication time or if it can be cambered in house for less. Or in this economy it might be the only work in the shop.Last edited by mindstometal; 12-08-2011 at 05:08 PM.Reason: spellingDan LindersVice President - Linders Specialty Companyhttp://[email protected]
Reply:We just cambered w44x455 beams to nys dot spec , using heat only 1100 deg max. 4 inches. Just takes time the biggest beams made. We have a 250 ton bulldozer to strighten and bend material. John Lutz and Griner Ind have big rolls to roll to radius cannot use in New York Steel Construction Manuel. John
Reply:I bet you won't do this with a rosebud...
Reply:Heat cambering has been around for a long time and always will be. As a layout man for a large fabrication shop, I had to do various cambers on all sizes of beams. Once you do a few, you kind of get the feel for it and know where to heat it. Smaller cambers i would only heat a few spots on the flange, and larger ones would require the wedge method. Sometimes an inspector would stand there and make sure it was below 1300 degrees before you misted cooling water onto the hot spots.CERTIFICATIONS:7018M- H.V.O10718M- H.V.O11018M- H.V.O9N10- H.V.O71T-1-HYM- H.O.V100S1 PULSE ARC 0,035- H.O.V100S1 PULSE ARC 0.045- H.O.VER70S-3 PULSE ARC 0.035 H.O.VER70S-3 PULSE ARC 0.045 H.O.VER5554- H.O.V
Reply:all the beams i've had cambered were done by the fab shop with a press. the largest was a w30-i don't remember the weight-x 60'. it was specified to have 3" of camber. we did three of them to use in a SIP house with a 60' clear span. the same shop did 2- w8x35-60' with 30" of camber for a little bridge project a couple of years ago.Doing steel in springfield, mo.I only drink when I'm by myself or with somebodymiller deltaweld 452 w/s62 and xr-wmiller trailblazer 302lincoln dc400 w/ln7eutectic tig rig hypertherm 900lincoln stt II w/ln742 |
|
发表于 2021-9-1 00:03:11