The landscape is changing for robotic press brake bending. A decade ago, bending automation was viewed as risky because of the significant investment and support required to realize an efficient and consistent bending process.
Recent strides, however, are paving a path toward greater adoption of robotics in press brake operations. New machine, software and robot technologies are making bending automation a practical solution for fabricators as they look for ways to optimize workflow, reduce turnaround time and lower their per-piece costs.
Going offline
Today’s programming software for robotic bending is more powerful and much easier to use than the software of 10 years ago, and those advancements have simplified CAM program preparation, creating robot trajectories, and machine setup and operation. Programming a robotic press brake can be handled completely offline with no need to physically teach the robot the machine setup or bending of the first part.
This eliminates considerable downtime and ensures that the throughput of the press brake bending cell is not interrupted. The software automatically generates the robot’s movement, directing it from one bend to the next to form the part and then to offload or stack the part. The software is able to calculate a complete collision-free path – generating the robot’s trajectory through all positions.
More than programming the robot, software with CAM 3-D virtual production simulation capability provides a complete walkthrough of the robot and press brake functions so the user can check and visually confirm the bending sequence before bending begins. Before a piece of metal is formed, the process is verified, avoiding costly mistakes and material waste.
Another advancement in robotic bending is a faster design-to-part process. The press brake bending cell in Figure 1 takes 10 min. for CAM generation of the bending and robot program and 10 min. for setup and first part generation – a total of 20 min. from “art” to “part.”
That’s a result of the tight integration between the press brake, robot and easy-to-use, intuitive software. Even with parts positioned and manipulated by the robot, the bending cell minimizes the time from design to formed part so that the bending cell is significantly more productive than earlier designs.
Universal gripper
The robot gripper is a critical component of a robotic system as the go-between for the robot and the part. Gripper designs of the past, however, did not have the flexibility to accommodate the many part geometries of bending. That meant investing in a number of different grippers to handle different part geometries and then taking the time for the gripper changeover, which could involve multiple changeovers per part.
Fortunately, new gripper designs are much more adaptable. For example, the gripper shown in Figure 2 is a patent-pending universal design that fits part sizes from 30 mm by 100 mm up to 350 mm by 500 mm and handles a maximum part weight of 3 kg.
This adaptive design enables the robot to process a series of different geometries without needing to change the gripper. It’s possible to make bends on three sides of a part without regripping. Use of a universal gripper not only saves on investment cost but also saves costly changeover times between grippers.
Robots themselves have also improved in terms of capacity and reliability. One of the world’s leading robot manufacturers offers more than 100 industrial robots with a payload from 3 kg up to 2.3 tons and maximum reach up to 4.7 m. Figure 3 demonstrates how an industrial robot with a large range of motion on a linear track up to 15 m has much more reachability than systems of old.
Cost of automation
Despite advances in function and flexibility, a robotic press brake bending cell still represents a sizable investment. In order to generate a healthy ROI, fabricators need to ensure that the ratio of the cost of the automation is not more than twice the cost of the standalone machine. Getting this ratio right keeps the direct cost of the part at a sensible level.
Also worth considering is the versatility of the system. A bending cell with the flexibility to operate in standalone mode when batch sizes are too small to benefit from robot automation will be more productive and profitable and, therefore, easier to justify.
In this scenario, the user can operate the robotic bending cell lights-out overnight or after hours and during normal business hours, they can work in either mode (with the robot or with the robot parked). In the bending cell shown in Figure 4, programming is handled with 3-D bending software so that the same program can be used for bending with the robot or for manual bending.
So what jobs are best for a robot? Surprisingly, it’s a fairly broad range of applications. High-volume repeat jobs, low-volume jobs that are reoccurring and jobs that are heavy duty can all make sense.
The flexibility of today’s bending automation technology makes it possible to run a variety of bending jobs profitably. For fabricators thinking that bending automation may be a good solution, it’s best to consult with an equipment supplier.
