Electromagnetic safety brakes linear axes

Whether loading and unloading machine tools or machining centres, for parts transfer or the transport of devices, tools or machining systems - the new modular axis and gantry construction kit of Fibro Lpple Technology GmbH (FLT) is designed for use in a wide spectrum of industrial applications. Boris Bind, Head of Design Mechanics & Development at FLT in Hassmersheim says: "The distinctive feature of FLT is that we produce automation solutions for a wide variety of industries and for all machining and handling processes. With our modular concept, we can flexibly address customer requirements."

Safety for people and machines

One component of the tried and tested modular construction system is the new LGR-3 linear gantry robot for machine configuration and for handling workpieces. Describing the range of applications Bind says: "With the linear gantry robot, we can automate individual process cells. The advantage of a gantry construction is that it is set up above the machine tool. This means that access to the machine and the work area remains free - contrary to a classic robot, which occupies a lot of space. Depending on the design and construction type, the variant as area gantry robot can bridge larger working areas. Under certain circumstances the gantry also crosses some areas in which people are present. The linear brake in the vertical axis reliably prevents the axis from falling and harming people. The gantry is therefore also considered safe for these application cases."

Safety thanks to the fail-safe principle

In the electric version of the linear gantry robot, FLT relies on the electromagnetic ROBA-linearstop brake by mayr power transmission, the specialist for brakes, clutches and couplings from Mauerstetten in the Allgu region. In case of power failures or emergency stops, the brake holds the axis in any position. It operates according to a fail-safe principle, i.e. it is closed in de-energised condition. The braking force is generated via thrust springs.

Compact brakes with backlash-free force transmission

As a compact brake unit, the ROBA-linearstop can be integrated into existing machine and system designs easily, quickly and without complex adjustment work. It acts on a separate braking rod. When the brake closes, the rod is held backlash-free. The ROBA-linearstop operates without a self-reinforcing wedge effect and therefore acts in both movement directions. The axis does not drop on closing thanks to the force generation without a self-reinforcing wedge effect, together with very short reaction times. Other linear braking systems which operate using a self-reinforcing wedge effect generate a high braking force, but the wedge effect only functions in one direction and the brake must "reset" to generate the wedge effect on closing. If the wedge effect of the brake is not limited, then the braking force increases infinitely, and the machine construction must absorb this impact. Furthermore, the clamping device must often be cleared with enormous force to release the brake. This is not necessary with the ROBA-linearstop. Boris Bind says: "It is important for us that the peak load which occurs during braking is not too high. We require a constant force progression during braking, which means that the console can be smaller. Moreover, the brake must be compact, because there is little overall space available."

Tested quality

The linear brakes available on the market today mainly act as static clamping units and are designed to hold the axes at a standstill. People can therefore work under suspended loads, also during commissioning, maintenance or even during production processes without the load having been transferred onto the mechanical linear brake. If a complete failure occurs during these operating conditions, then the linear brake alone is responsible for the safe retardation of the load. Therefore, the ROBA-linearstop safety brakes, which are available in electromagnetic and also pneumatic or hydraulic versions, are more than just clamping units. They are designed to reliably hold the load and are also suitable for emergency braking. Prior to the brake leaving the mayr power transmission works in Mauerstetten, the required force is set with the corresponding safety level. This value is checked and documented, meaning that every serial number is traceably allocated. To enable this, the company has multifaceted, modern test possibilities and can call upon decades of experience in development and construction. The electronic database in which the measurement values are archived together with the associated serial numbers of the product guarantee 100-percent traceability.

Please visit www.mayr.co.uk to learn more.