Compact cable guidance for tight bend radii in a Trumpf bending machine

Profile

• What was needed: R4.1L e-tube
• Requirements: supply of motor, encoder and sensor cables and earth cables with minimal bend radii and a system that is very easy to assemble, a design that is as compact as possible and still enables a high number of cables to be guided
• Industry: machine tool manufacturing
• Success for the customer: low assembly effort and costs, simple maintenance despite closed system, minimal bend radii at high filling volume, extremely easy energy supply that requires very little drive energy, no storage costs thanks to fast delivery from stock when an order is made

With bending machines from the TruBend Series 5000, press forces of 50 to 320 tons and edge lengths of 1.25 to 4 meters are possible. R4.1L energy tubes from igus are used to supply the bending device.

Problem

The TRUMPF company is one of the world's biggest machine tool manufacturers and has around 70 subsidiaries. TRUMPF Maschinen Austria was founded in 1992 in Pasching, Austria, the "centre of excellence for bending" in the TRUMPF Group. Here, the company now makes various types of bending machines in different sizes. The products are a symbol of the highest level of experience and innovation in bending technology.
Amongst other things, the TruBend 5000 series bending machines are built here in Pasching, of which more than 600 systems are manufactured each year. Press forces of 50 to 320 tons and edge lengths of 1.25 to 4 metres are achieved with this all-round machine. The strengths of this system become obvious especially with large-sized components: in particular for bending large or heavy parts, operators of the TruBend Series 5000 can use a bending tool, on which the sheets to be processed are placed. This supports up to 30 degree angles and can be automatically adjusted in height.  "For large and very heavy workpieces, this support is necessary to bend the sheets accurately, requiring only one operator", explains Volkmar Schmidt, Head of Technical Purchasing at TRUMPF Maschinen Austria. The bending device can be moved freely from left to right.
To guide the motor, encoder and sensor cables as well as earth cables safely alongside the machine, the machine tool manufacturer was looking for a suitable supply solution, which did not only have to meet requirements regarding ease of assembly and minimal bend radii of the cables. The solution also had to be able to carry a large number of cables while being as compact as possible.

Solution

In order to move the mentioned motor, encoder and sensor cables as well as the earth cable alongside the machine safely when the bending device is moved, TRUMPF now relies on energy chains from igus. For the TruBend Series 5000, the machine tool manufacturer sources the chains as enclosed tubes from the R4.1L series, using overlapping lids instead of the standard crossbars. Just as with the open E4.1L version, the lids can still be opened at both ends and pivoted upwards by 115 degrees, which saves assembly time and cost. If necessary, they can even be removed completely, fitted again and closed by just pressing them shut.
The e-tubes were originally developed as a swarf-resistant version of the e-chain. In this specific application, however, TRUMPF wanted the closed version for mere optical reasons.  Other important factors for the machine producer are not only the ease of assembly and the small bend radii of the energy chains, but also the maximum filling volume combined with smallest possible exterior height. When compared to the heavy-duty chain E4.1, significant mass could be saved using the E4.1L so that the otherwise identical e-tubes were around 30 per cent lighter. This not only saves users a lot of drive power. It is also possible to accommodate even more cables and hoses in a given space.
However, the patented interlocking undercut design of the chain links and the double stop-dogs with large surfaces were carried over from the E4.1. These design features provide high strength and also allow for larger unsupported lengths. By means of a brake in the stop-dog surfaces, the rolling noise is also minimised, which resulted in a very quiet operation of the chain.

A look into the inner workings of the bending device: motor, encoder and sensor cables as well as an earth cable are guided in igus e-chains and supply the bending tool, which is completely manufactured at the Linz site.

Benefitting from the igus products and service for years. Volkmar Schmidt, Head of Technical Purchasing at TRUMPF Maschinen Austria (left) together with Elvis Kaufmann, Technical Sales Consultant at igus Austria (right).