Large parts need large Press brakes bending

Large parts need large Press brakes bending


This press brake is a 4,000-ton, 47.5-ft. model that has work supports, front and rear plate positioners, and a gooseneck punch with rollers for quick die change and tooling storage.

Large job needs large press brake for sheet metal bending applications

And, customer needs can be varied. some of the uses for these mammoth machines include forming parts for barges and ships, power transmission and distribution poles, and telescoping crane booms.

All of these products are typically formed on tandem press brakes. Tandem press brakes are two press brakes that are aligned end-to-end, and can be used as single machines or synchronized to run together.

For instance, barges are typically fabricated using 40-ft. plate and are often formed on tandem 20-ft. press brakes. Power poles are fabricated on tandem brakes as long as 60 ft., and telescoping crane booms can be made on tandem brakes or single machines up to 60 ft. long.

The sheer size of these parts can be back breaking, a problem that press brake manufacturers have solved with various methods over the years.

There are many older machines [in the field] being used to make power poles with varying degrees of automation,They range from completely manual machines where the [metal] sheets are positioned with an overhead crane and men with pry bars to machines with tables front and back with manual sheet positioners with joysticks.

 A typical setup consists of tandem 30-ft. press brakes with an in-feed conveyor with four material pushers on the front of the brakes and material supports with four pushers on the rear of the machine. An automatic loading device positions a sheet on the in-feed conveyor, which moves the part over a lower die. At the same time, the rear pushers trap the part between the front and rear pushers and the material is measured with mechanical or laser equipment depending on the model. After the size is confirmed, the part is positioned and formed. Then, a part extractor removes the part onto an exit conveyor. Ursviken also has supplied systems whereby the extractor has the capability to bring in the new trapezoidal bent part while pushing out the formed pole.

These types of press brake applications require considerable time to load and reposition the sheet, check bend angles and remove the part once it is formed, Rose says. Moving from part to part requires accurate bends, and to attain that requires material handling, measurement, positioning and other factors.

Overcoming challenges

Press brakes, in general, can have some challenges, such as angular accuracy, springback and deflection, but these are magnified by the sheer dimensions of the metal that these giant machines must bend.

To this end, we have developed a quick die-change upper tool system with rollers that minimizes friction and makes it possible to change large, heavy upper tools within minutes. This tool system can also be complemented with an upper tool holder for storing tools when they’re not in use.

We also offers a fully automatic CNC lower die system, the multi-purpose variable die tool (MP-VDT) that adjusts the V opening and has rollers in the bed that make long, heavy tooling easy to push in and out of the press brake. The MP-VDT, is a fully programmable lower die that can achieve setup reductions of 80 percent or more. It uses interchangeable, sectionalized anvils and multiple die openings in the same setup.

In addition,  developed an angular control system that differs from conventional crowning systems in that there are multiple wedges that are separately driven to achieve the principal of crowning. This system allows for fine crowning adjustment over the entire press brake regardless of machine length.

Also has a non-contact laser angle measurement system that works with an advanced press beam positioning system. When forming high-tensile plates with a high degree of springback, the system can accurately adjust the bend angle, taking into account the springback. No matter the properties or thickness of the material, the system enables an exact determination of the bend angle with an accuracy of better than ±0.3 degrees.

This patented system is active throughout the bending cycle to ensure angular accuracy regardless of material variations and forming conditions. It’s available for single V dies or can be integrated into the MP-VDT. The system can be user configured with multiple stations to measure at strategic positions along the bend line.

The bend angle is measured by scanning the projection of a laser beam to the surface of the sheet metal with a CMOS camera. The angle between the laser and the viewing axis of the camera defines the correlation between the position of the line in the camera image and the angle between the sensor and the sheet. With a second sensor at the opposite site, the bend angle is calculated.

Material handling

It  can supply a variety of rear and front gauging as well as supply material supports in the front and rear of the press brake. The CNC controlled support systems not only act as a support arm, they also ensure accurate material positioning for bending. For larger parts, heavy-duty plate followers that are synchronized with the press beam to support the material can be added, Rose says. The followers automatically follow the speed of the ram throughout the bending cycle. These features significantly improve part accuracy and reduce operator fatigue.

The high-velocity rear gauges possess a huge strength-to-weight ratio with minimal intrusion into the forming environment. Travel limits have been extended in all three dimensions (X-R-Z) and enhanced gauge fingers increase the gauging versatility. Ursviken’s 2-D Smart Gauge with full-length gauge ruler makes it possible to bend several small pieces at the same time. Gauge fingers can be fitted.