Unison is launching what it believes to be a unique concept on the tube bending automation market. The Evbend machine reduces the entry costs to precision rotary draw tube bending by using manual operations to feed and rotate tubing and apply the bending force, but with smart CNC-controlled braking on the carriage feed, rotation and bend arm axes to ensure part shapes are formed with high accuracy.
The development is a re-engineered version of an existing machine called Evbend. The Evbend concept was originally developed by a UK engineer in the 1980s. Unison acquired the intellectual property for Evbend in February 2014. It has now re-engineered the machine to add a modern programming and operational control user interface, and to enhance manufacturability. Unison believes the new machine – the Evbend 1000 – is the simplest high-precision CNC tube bending option available today for small-diameter tubing up to 22mm.
EvBend bending technique – and the rigidity of the machine – is suitable for producing high-precision tubular parts in a low-volume production environment. Since its introduction in the 1980s, it has attracted a large user base, with more than a hundred machines sold worldwide, predominantly into aerospace and motorsport sectors for small-batch production, prototyping, and for repair or reverse-engineering purposes.
Manual operation makes Evbend exceptionally versatile, simple and safe. There is almost no limit to the intricacy and multi-bend complexity of tubular shapes that can be formed, thanks to the machine’s ultra-compact bending head, and the versatility that manual operation brings to the manipulation process. However, the ease of use of Evbend is probably the machine’s strongest selling point.
There is no complex user interface to learn. Operators can typically grasp how the machine works within minutes. Users can create bending programs in two ways. First, by entering the standard tube bending information (XYZ/YBC values, or the distance tube is fed out, rotated, and the angle of bend) into dialogue screens on the Evbend’s Windows operator interface; this data can also be transferred from a coordinate measuring machine. Alternatively, users can program the machine using a teaching mode. This latter method is particularly powerful: it is so simple to use that a part can be reverse-engineered by bending and comparing a tube against an existing part – with the user capturing the underlying material feed, rotation, and angle of bend information as the desired points are reached.
Precision and repeatability
Once the bend data is entered the user can start bending parts, under the interactive guidance of the machine. Evbend’s new touch-screen HMI displays the actions required in sequence – with real-time feedback of positional data as tubing is fed, rotated or bent. The precision and repeatability of these feed, rotation and bending operations is assured by a smart electromagnetic braking system. Encoder feedback on each axis ensures that all movements are made with extreme precision. Evbend’s pneumatically controlled mandrel is automatically applied during the bending cycle – with programmable control over mandrel withdrawal.
As standard the machine is supplied with a right-hand bending head. However, Evbend can also perform left-hand bending with the addition of an optional second bending head.
The major element of Unison’s upgrade to the Evbend machine is the provision of a state-of-the-art Windows HMI. This replaces a previous dedicated controller and operator interface, which required the connection of a separate PC to run the bending program database. Unison’s new HMI meets the demands of existing users for a fully integrated machine. It also brings many attractive new features to this tube bending machine concept including improved graphics, touch-screen control, simple integration into factory networks, and access to Unison’s powerful CAD tools and interfaces for the automated creation of tube bending programs. The new HMI is also available as a retrofit for Evbend’s existing user base in aerospace, motor racing and other precision tubular manufacturing sectors.
Alan Pickering, Managing Director of Unison says: “We are truly delighted to have secured the rights to this versatile precision bending machine – it’s a great complement to our well-known range of all-electric tube benders. We have not yet found a part shape that cannot be formed on the machine, and the addition of our new HMI substantially extends the ease of use and production efficiency of the machine.”
Unison is also working on a larger version of the Evbend machine, which will apply power assistance on the bending axis to allow tubing of up to 50mm/2 inches in diameter to be manipulated. For more information visit www.unisonltd.com.