Panel benders with high productivity and quick tool setup are distinguished by their speed, flexibility and economic benefits, especially for small lot sizes. By Simon Hiebl, Trumpf
Different bending methods have their own advantages. To select the perfect technology, it is important to know what the customer produces. In the past, the decisive criteria were primarily the production quantity and thickness of the material. Now, the manufacturing trend is moving towards small lot sizes.
This plays nicely into the hands of semi-automatic machines. Their advantage is that they can be run more quickly than fully automatic machines. This is relevant especially for small lot sizes. In these semi-automatic units, the blank holders are changed automatically. While the operator is preparing for the next component or starting the program, the machine automatically changes the blank holders.
Incidentally, Trumpf is making its debut in the market for panel bending technology. The panel bending machines in the TruBend Center Series 5000 are semi-automatic machines. This means that the machines automatically carry out all the bending steps for each bending edge. The operator only needs to insert, rotate and remove the blanks. Everything else is done by the two-axis part manipulator, working automatically in conjunction with the bending tools.
One Tool For Different Bending Radii
In the past, incorporating differing radii in a single component was often avoided since such items could not be manufactured economically, and the component therefore had to be made by putting two separate parts together.
With panel bending, it is now possible to generate differing radii in a single workpiece very quickly, and without extra tool setups. This raises productivity and is a good way for designers to realise their wish for larger rounded areas in trim panels and satisfy requirements for exceptional geometries.
From Small To Large Sheet Metal Components
Among the materials typically processed with the TruBend Center Series 5000 are mild steel up to 3 mm thick, stainless steel up to 2.2 mm, and aluminium up to 3 mm. Galvanised and painted sheet metal can also be processed.
The machines in the series can not only bend large parts, but are suitable for bending small components. The minimum component depth (ie: profile width) can be as little as 40 mm. Here, the machines once again capitalise on the benefits of the semi-automatic design, since the narrowest profile width for fully automatic machinery is about 120 mm.
Narrow bends and the ability to process smaller parts are also, quite clearly, assets offered by the panel bending machines. They cover a broad range of applications while in the past, certain parts had to be manufactured on other machines.
Examples include door frames, small sheet metal components for agricultural use, and electronic equipment casings. It is also possible to process sheet metal components for household appliances, for workshop or retail fittings, commercial kitchens, automobiles, building facades, all kinds of automatic equipment, and much more.
The machine’s flexibility makes it possible to produce small and large components, narrow and broad bent sections, and a variety of radii without having to change tools. That expands the operating range tremendously and, in turn, boosts the utilisation rate of these machines.
High Precision Manufacturing
Finished material and polished or brushed stainless steel, in particular, have proved to be very sensitive to scratches. Here, the panel bending machines are suitable for this application because they are precise and use bending tools which are robust and mechanically stable. This means they can process with a minimum of tool marks.
Another point to note is the accuracy of repetition for these bending machines, which are precise to the hundredths of a millimeter. The bending quality is high enough for laser welding to be carried out immediately afterwards. One of the reasons for the high quality is an integrated video camera functioning as an angle assistant.
This makes it possible for the operator to compare the actual and specified bending angles and to make corrections as needed. In addition, it is possible to make enhancements in quality for the following bends since the operator can use the first bend as the basis for a very exact angle comparison.
With the rejection rate significantly reduced, the manufacturer says the very first part meets specifications. This is particular important when it comes to short production runs.
Adjusting Height To Enable Negative Bends & More
Certain panel bending machines come with a height-adjustable two-axis part manipulator — a component can be bent in a number of different ways, at different edges. Here, even negative bends are possible, and this feature is totally unrivalled.
In fully automatic machines, a sheet must always lay flat to accommodate rotation through 90 degrees. This means that sheets with upward and downward bends can be processed only on semi-automatic units like those mentioned above.
The height-adjustable two-axis part manipulator also offers further advantages. Different gripper modules — including mechanical clamps, magnetic holders and vacuum grippers — can be mounted. Since the height can be adjusted, even smaller components can be secured on an edge which has already been bent. The result, as previously mentioned, is that the machines can bend narrow profiles, right down to 40 mm.
The panel bending technology shows its benefits whenever the blanks to be bent have raised areas or recesses. In contrast, fully automatic units could encounter problems gripping parts if they have punched openings in the middle. These are the fundamental reasons that make the panel bending technology flexible and economical.
|MagicShoe: Redefining Comfort|
Question: How do you replace that foot switch? Answer: By attaching that switch to your foot. While manufacturer Trumpf is not going to surgically attach a foot switch to your foot, they have come up with a shoe that houses a sensor system, which in turn helps operate the pressbrake.Developer Dr Klemens Freudenthaler, predevelopment at Trumpf Maschinen Austria said the reason for coming up with a ‘MagicShoe’ is to help operators go about their work in a more comfortable manner.“The position of the foot when operating a tethered switch is not very ergonomic. Moving the pedal around all the time is inefficient and annoying — especially when executing sequences of bending operations,” he said.According to him, the team developed and evaluated all kinds of ideas during the brainstorming phase but eventually concluded that the stroke would have to be triggered by the operator’s foot, since the hands are always busy positioning and holding the sheet metal component.Even though the primary objective of the shoe is to improve ergonomics, safety requirements are important considerations too.“Since the MagicShoe communicates wirelessly with the press brake, the interface has to meet the same high safety standards. Additionally, we had to ensure that the operator was inside the machine’s operating range when actuating it with the shoe. Neither could the machine ever be tripped by accident. This meant that the operator’s foot movement to start the bending process had to be as safe and unequivocal as possible. Finally, the shoe had to be as comfortable as a standard safety shoe,” he said.Like all inventions, the development stage was a challenging one and Dr Freudenthaler had his fair share of stumbling blocks.
“The greatest challenge by far was finding a motion pattern that the operator could perform as easily and comfortably as possible and that nevertheless fulfilled all the safety requirements. The second difficult task was designing the mechanical elements for the sensor system built into the shoe,” he said.
The solution, in a nutshell, was to test the product thoroughly. He said: “We tried it out and refined it, working with colleagues from our in-house metal shop. The goal was to examine ergonomics and efficiency under production conditions. During this period, we never failed to consider whether the release pattern was indeed safe. Under no circumstances could it be possible to actuate the press brake by accident. At one point, the team collected measurement data for the routine foot movement patterns of 40 test persons. The team investigated these after each development step to make sure that the new triggering motion was not among these movements. The release pattern fulfils the safety requirements only if it is not in the measurement data.”
APMEN Fast Fab