Press Brake Advancements

The ability to close the loop of trial and error using CAD packages and offline programming software is one of the major changes to come to press brakes recently

October 1, 2009

For many companies the bending process starts with the design of a part in 2-D or 3-D. The part is then cut by a laser, punch, or other means, and finally the part is bent. What can occur, however, is that the final part is not the correct size or shape, and the process must start all over again.

This does not have to be the case.

“In the past most shops would develop a part by means of a DIN formula or specific bend deduction value related to a material type and thickness,” explained Shane Simpson, product manager for bending for fabricating equipment supplier TRUMPF. “The problem that occurs is that the variation of tooling that is selected at the machine by the operator can completely change a part’s development, making the final bent part out of tolerance.”

The part’s designer may not recognize the fact that a tight die or specific radius can determine which tools are selected and these variables cause bend deductions to change. The ability to design a part with tools applied before you unfold allows the part development to be almost exact because the blank development is based on the tooling applied rather than a standard formula.

The next advancement comes with the ability to see the part in a virtual world by means of offline programming. This type of view will show whether or not the tools that have been selected will make the part properly before a blank is ever cut.

According to Simpson, seeing the part can reduce your scrap rate to nearly zero because you know beforehand which tools are required, and the operator is already certain which tools should be used. This eliminates that variable, and bend sequences, shown in 3-D at the control, show the operator how to process the part, which has already been proven offline.

Bending Challenges

Like many other jobs in fabricating, skilled press brake operators are becoming more and more difficult to find. Many new operators learn their trade on the shop floor which can create issues for business owners because scrap rates can increase and efficiency decrease.

A lack of skilled operator makes offline programming more important.

“If there are multiple brakes in a shop, it is possible to have one programmer creating the proper bend sequences and tool setups,” said Simpson. “This reduces the need for a highly skilled operator. This, combined with precision tools, hydraulic clamping, and 3-D visualization at the control can make a lower-skilled operator very efficient and more cost-effective.”

No longer does the operator need to be a sheet metal mechanic to run a press brake efficiently as long as the proper machine and processes are put in place. In the future robotics likely will be used more frequently in the bending process making repeatability and quality even better.

“The operator will not be in the danger zone or lifting heavy parts but acting more as a liaison to change tools and skids of parts and programming offline,” said Simpson.

Short-run parts will still be difficult to produce on a robotic system because an operator is much more efficient in these circumstances.

“In the distant future with tool changers, programming techniques, and production plans evolving, going hands-free at the press brake will someday become a reality,” he added.

Tool changes, parts with complex geometry, very short lot runs, and part sizes and weights are currently the limiting factors to robotic bending. Programming offline instead of teaching the robot at the machine has become an extremely effective way to counteract some of these obstacles, but automatic tool changing for all types of parts, not just small ones, still needs to be addressed in the industry.

“Offline software has allowed us to take the lot sizes down significantly because the programming is very fast, easy, and precise,” said Simpson. “We have also addressed changing from job to job by means of an automatic gripper changer in combination with a production plan. The possibility to set up multiple jobs by stage bending allows us to overcome some of the automatic tool-changing issues that currently create an obstacle.”

For more information, visit www.us.trumpf.com.