One-piece bend dies are the longest wearing and best performing dies, which are usually, (but not always), dedicated to a specific part. Because of their one-piece design, they typically leave fewer marks on the tube.
A platform bend die accommodates a small center line radius, thereby eliminating the center stud. This design is also helpful to add in support. Inserted bend dies have a replaceable grip section to avoid replacing an entire bend die. For a versatile tool, different length inserts can be made to change grip lengths.
The key thing to remember about bend dies is that the more versatility designed into a tool, the fewer things it can do well.
Elliptical bending is not for every situation. It is a very specific solution which depends on tube O.D., (Outside Diameter) wall thickness, C.L.R. (Center Line Radius), and material and product specs. Bending with an elliptical shaped tube groove can eliminate the need for a mandrel, but comes with some cost.
Because it actually reshapes and resizes the shape of the tube, a lot of the machines ability is used up in working the tube. Therefore, a machine's elliptical capacity is only 5/8 of its round capacity. To see if bending without a mandrel is applicable, you’ll need to know some formulas.
To find the Difficulty Factor (DF):
Tube O.D. divided by Wall = Wall Factor
C.L.R. divided by Tube O.D. = Degree Of Bend
Wall Factor divided by Degree Of Bend = Difficulty Factor.
Once you know the difficulty factor, you can evaluate the elliptical feasibility per your material type and/or configurator data.
For more extensive information see our Nonmandrel Bending article. Because these factors, as well as the type of tube material affect the process, Tube Bending Concepts can customize shape geometry per your application, producing predicable results.
Square and rectangular tubing is usually bent using leaf tooling. Without leaf tooling, the vertically expanded tube will lock into the bend die. Once the leaf (or plate) is removed, the tube is free to be extracted. Split dies execute the same process, by splitting horizontally. This process is performed by utilizing a hydraulic actuator.
TBC Mfg. can make bend dies for multi-radius benders in individual stackable pieces or in one solid multi-radius die.
Compound grip section bend dies are helpful when gripping on a previous bend, on a bend with little to no amount of straight, or to orientate a tube for a second set up.
To assist in clamping, the grip area of the bend die can be altered with serrations or roughed up with grit blast. (Grit blast is not a material adding spray; it simply roughs the surface with an abrasive media.) Grit blast should not be confused with carbide spray which actually adds material.
Tooling from TBC Mfg. comes standard with reverse interlock. This achieves better bends, with less marking, by aligning the clamp die into the bend die and maintaining alignment of the pressure die during the bending process. This tube groove alignment also aides in set up.
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