As a leading HSS tube manufacturer, Bull Moose Tube delivers precision-engineered HSS steel tubes that meet stringent industry standards, ensuring reliability and performance in every application.
Xin Jiyuan are exported all over the world and different industries with quality first. Our belief is to provide our customers with more and better high value-added products. Let's create a better future together.
In addition to the standard A500 range of HSS steel tube, our comprehensive line also offers several specialized choices. These include HSS A products with enhanced strength and tighter tolerances for critical structural applications, low-maintenance weathering grade HSS, and the ultra-light/ultra-strong Stratusteel.
Bull Moose is the only HSS producer that uses both direct-form and round-to-shape (indirect-form) manufacturing methods. This gives customers the option for weld seams on most of our products to be either on the short side (direct-form) or the long side (indirect-form).
With multiple manufacturing facilities across the U.S., Bull Moose stands as a trusted HSS tube supplier, committed to providing timely rolling schedules, and reliable ship dates for our customers.
Stratusteel® from Bull Moose® is revolutionary hollow structural steel tubing that’s three times harder than conventional steel and achieves strength ratings in excess of 100 and 110 KSI…at a weight that’s as much as 35% below other steel.
This robust technology enables cranes to reach higher, trailers to carry more weight, rescue ladders to extend farther — all without compromises in strength.
TOUGHER: Stratusteel® is 3x harder than standard steel as measured by the Rockwell hardness scale. As a result, products made of Stratusteel® have an impact-resistant toughness that enables them to take a beating and look newer, longer. This hardness also enables extendable products (such as booms and fire truck ladders) to extend farther without sway or bounce.
CREATES VALUE FOR YOU IN SIGNIFICANT WAYS: For truckers, less weight = more freight. For booms, cranes, and ladders, it’s stronger so you can extend longer. For every application, it performs as some of the toughest, most urable steel ever, prolonging the life and value of heavy-duty equipment.
CURRENT APPLICATIONS: Military vehicles, launch pad scaffolding, ladders, booms, agricultural equipment, heavy haul trailers.
With the rising cost of galvanized steel, it’s good to know there’s a solid substitute: Weathering Grade steel tube from Bull Moose®.
Compare this stock to COR-TEN® and other ASTM A847 options, and you’ll find that our Weathering Grade steel delivers equivalent performance for heavy weather environments…cost-effectively.
Over time, the surface of this alloy steel develops a stable, light-brown patina that protects it from corrosion—and eliminates the need for painting and re-painting.
Its durability and 50 KSI strength make it ideal for applications such as walkways, bridges, railings, and other structures that are directly exposed to the elements.
Bull Moose Weathering Grade stock is readily available in multiple lengths, shapes, and wall thicknesses to fit an extensive range of projects.
Types of Tube Bending
In order to understand the optimum design characteristics for tube bending and manipulation manufacture it is important to appreciate the different methods of tube bending. There are fundamentally three approaches known respectively as compression bending, draw bending and roll bending.
Compression tube bending
Compression tube bending, is akin to bending a copper pipe around your knee; you are holding one end of the tube stationary and forming the tube into shape around the former (in this case your knee). The next step up is a simple manual pipe bending tool, a type often used by plumbers for copper tube. To produce more complex multi-bend components, for small diameter tube where it is possible to bend it manually, hand bending jigs use compression bending. Some quite elaborate shapes can be produced.
Once we move to larger diameters and stiffer material, like steel, then machine power becomes essential and draw bending is the normal forming method used. The key difference is that the tooling pulls or draws the tube around the former tool. In fact, rather than the tube being clamped behind the former it is clamped to the former and the clamp and former rotate with the tube drawn around the former in an arc behind it, just pressed to the former by a pressure die.
As the name suggests the pressure die is not clamping the tube it is just pressing it against the former but the tube can be drawn along past it. Draw bending overcomes some of the collapsing problems that can occur with compression bending.
Draw Bending
Draw bending machines can be simple NC (numerically controlled) or full CNC (computer numerically controlled). The critical considerations, for our purpose, are that the bend tooling must grip the tube precisely in order to pull it around the bend; this means that the tooling must be specific to the tube’s external diameter; and, the central former around which the tube is drawn must match the required bend; this means that the tooling must be specific to the finished tube’s bend radius.
Some thin wall (relative to diameter or material specification) tubing is liable to collapse when bent and with a draw bending process (in contrast to compression bending) it is possible to support the tube at the point where the bending is taking place by inserting a mandrel down the centre of the tube. For this reason draw bending is sometimes referred to as mandrel bending.
Roll Bending
If you need a very gentle curve, ie a large radius of curvature, then draw bending ceases to be feasible since the size of the tooling (and the machine to mount it on) becomes prohibitive. This is where roll bending, sometimes called push bending, comes into play.
Are you interested in learning more about Special Section Tube Manufacturer? Contact us today to secure an expert consultation!
It works by pushing the tube through, normally, three rollers – two on one side of the tube and one, between them, on the other. If the rollers are lightly resting on the tube then it will clearly just pass through them without bending, but as the roller pressure is increased the tube will begin to deform, becoming concave on the side of the single roller as the two outer rollers try to push it around the inner roller. The greater the pressure the tighter the bend.
So is draw bending better than roll bending?
Actually they both have their place because they do quite different things. Draw bending is for fairly tight curves, typical of most engineering applications, while roll bending is for large radius curves often found in furniture or architectural work.
One slight downside to roll bending is that there is a degree of trial and error involved in getting the right curvature, certainly the first time the job is bent, since every different tube diameter, wall thickness and material behaves slightly differently under force and because there is no fixed form that the tube is being bent around these factors come into play more significantly. Consequently there is a longer development time and more tube wastage, all of which ultimately has to be paid for, than for roll forming. Obviously this is not such an issue for larger volumes where the cost can be spread. Fundamentally draw bending is often considered more accurate than roll bending.
Armed with a good understanding of the different bending processes available we can now consider the selection process that a design engineer could undertake.
Bend Radii
When we talk about bend radius it refers to the radius measured to the centre line of the tube.
Every tube bender will have a different set of draw bend radius tooling based on previous jobs that they have done, but by far the most common will be in line with the first rule of thumb;
Standard draw bend radius is 2 x D
What that means is that if you have a tube OD (outside diameter) of 20 mm then the bend radius to choose, if you can, is 40 mm. It is possible to have a tighter bend radius, even as low as ½ x D, although anything below 2 x D will usually require costly tooling and probably mandrel bending.
At the other end of the scale the maximum draw bend radius is not dictated by the performance of the tube but more by what tooling it is feasible to fit onto the bending machine. Depending on the tube diameter this could be a very large multiple but again moving away from the standard 2 x D invites tooling charges.
If you need larger radius bends then push or roll bending could be the solution and the minimum radius that is really feasible with that is;
Minimum roll bending radius is 7 x D
It is technically feasible to be tighter than 7 x D but it depends a lot on wall thickness and material properties, so for safety stick to this guideline.
There is no maximum limit to the radius from roll bending, except of course leaving the tube straight, which is the same as an infinite bend radius!
Obviously it always makes sense to check with your tube manipulator what tooling they have for the tube diameter that you have chosen before you start designing your component.
Alternatively, wherever possible allow a wide tolerance in your bend radii. For example if you have a simple 90 degree bend in a 20 mm tube does it really matter to your design whether the bend radii is 40 mm, 50 mm or 60 mm? So why not label it as 50 mm +/- 10 mm.
Multiple bend radii
If you need more than one bend in your tube the next question to consider is can they all be to the same radius.
Basic draw benders are what is called single stack, that is they can only take one set of tooling, at a time. Now, it is technically feasible to make a bend with one radius tooling, remove the tube, change tooling to another radius and make another bend, but it is tricky to get back to exactly the same datum and you can see how much more time is involved, so it is rarely done.
We often see drawings that require two different bend radii that are, in reality, so similar that the difference would be almost unnoticeable; why would you design a tube with one bend radius of 70 mm and another of 75 mm? But people do. If you design with multiple radii only do it if you really need to!
If you must have multiple radii bends then you need a two stack, three stack or even a multi-stack machine (which can have as many tooling sets mounted above each other as will fit onto the tooling post, and can index between each of them). Obviously as you increase up the range of these machines you reduce the number of tube benders who will have that equipment.
A bend too far
Even when you have chosen standard tube dimensions, standard bend radii and kept to a limited number of different bend sizes, there are still bend configurations that will cause problems for tube manipulators and will often translate into higher costs for you. There is normally a way to produce most tube designs but some can be far more complicated to manufacture than you might imagine. In some cases the only way your tube will be able to be produced is in sections and to be joined. A good weld joint, properly dressed will be all but invisible, but obviously adds to the cost, so if you can avoid it so much the better.
It would be impossible to list every tube configuration that might be problematic but a few possibilities are;
“Knots”
If there is a loop of tube with the tube then passing through it in some way then it is highly unlikely that it can be produced on a standard CNC bending machine. It is sometimes possible to produce this sort of thing on a hand bending jig in one piece, but you will definitely face tooling costs, and even this will be limited to smaller diameter tubes which can be hand-formed. Alternatively it may have to be made in separate pieces and joined.
Want more information on Industrial Steel Products? Feel free to contact us.
Comments
Please Join Us to post.
0