| Press brake bending is simple stuff: An | | | | Rocker dies are essentially simple dies - with a |
| arrow-shaped punch presses a sheet metal blank | | | | twist: The top die has a built in 1-axis joint, which |
| into a v-shaped die, thereby forming an angled | | | | allows it to enter a bottom die with a partially |
| bend. Or maybe, if we are getting adventurous, | | | | obscured opening. This makes it possible to form |
| we could imagine something like a gooseneck | | | | a channel in one pass, even if the flange is very |
| punch making return flanges, but that is stretching | | | | long - something that (depending on the shape of |
| it as far as it goes, right? | | | | the part)might not be doable in a traditional |
| No, not quite. Press brake tooling has come a long | | | | channel die set. In that case, rocker dies provide |
| way in recent years, and can do a lot more than | | | | the benefit of reduced setup time and fewer |
| it used to, and probably a lot more than you think. | | | | operations in order to shape the part. |
| Some of the more interesting techniques include | | | | The term 3 point bending is used about a special |
| wiping, rocker dies, 3 way bending and elastomer | | | | type of die set, in which the bottom die has an |
| bending. | | | | element which can be adjusted in height by a |
| A wiping operation consists of more than one | | | | servo motor. The top die is buffered from the |
| movement, unlike simpler shaping methods. A | | | | ram with a special hydraulic cushion to |
| special die set is used, where the bottom die has | | | | compensate for little variations in the thickness of |
| movable elements. As the punch moves down | | | | the blank. Together, the two dies make it possible |
| and executes the first part of the bend, the | | | | to attain extreme precision in the angles bent - |
| bottom element receives the blank and is pressed | | | | down to 0.25 degrees. This type of tooling is |
| down on its springs. This motion activates an | | | | expensive though. |
| element on the back of the die, which now | | | | Elastomer bending is especially interesting. Here, |
| moves in and executes the second part of the | | | | the bottom die isn't steel, but a flat piece of |
| bend. A good example of the application of this | | | | synthetic material which serves to wrap the blank |
| technique is the making of a radiused return | | | | around the punch, as it comes down. The resulting |
| flange: The blank is pushed down on the first, | | | | bend radius will be very close to the punch radius, |
| springloaded element, and the resulting downward | | | | as there is little springback. Also, the elastomer |
| motion bends the blank to a right angle with a | | | | pad does not mar or scratch the blank. |
| radius at the bending point. The second element | | | | These are some of the techniques that keep |
| then comes into play and finishes the job by | | | | press brakes relevant in today's sheet metal |
| folding the edge of the blank over, creating a | | | | fabrication work. |
| return flange in the process. | | | | |