In the newly developed Krause + Mauser rotary transfer machine "Reflex" for the machining of steering knuckles, the play-free "Roba-guidestop "profile rail brakes by Mayr Antriebstechnik for highest functional reliability. The brakes act directly on the moving masses of the vertical axes and thus provide reliable protection for people and material.
The corporate group Krause + Mauser supplies numerous renowned car manufacturers worldwide with specialized, highly productive machines. At the locations in Vienna and Oberndorf am Neckar, the renowned mechanical engineering specialist designs and produces systems and machining centers for the production of all powertrain parts of a vehicle such as parts for engine, transmission, clutch or suspension axles.
The company has recently developed a new type of machine in the form of a rotary transfer machine with efficient machining technology for the production of steering knuckles, wheel carriers, cylinder heads and other workpieces. The clearance-free Roba-guidestop profile rail brakes from Chr. Mayr GmbH + Co. KG from Mauerstetten, which are used in the vertical axes of this machine, reliably protect against damage.
The rotary transfer machine has a total of up to six stations, one for loading and unloading the workpieces and up to five processing stations. "The basic unit of each processing station is the same. At each station, however, different tools are used, with which different processing steps are performed on the workpiece, "explains Gerhard Rausch, Group Manager Mechanical Design at Krause + Mauser in Oberndorf. Each processing station has a crown turret with eight tool places each. "The individual workpieces made of aluminum in the rotary transfer machine in each case two revolutions, then a pair of knuckle - one left and one right - finished".
So nobody gets hurtTwo Roba-guidestop safety brakes are located on the vertical guide rail of each processing station. The brakes of size 45 have a nominal holding force of 15 kN and serve as holding brakes during operation. "The main task of the safety brakes in our rotary transfer machine is the protection of persons.
The two brakes, as a redundant system with two independent brake circuits, meet the guidelines for personal safety without any problems, "explains Gerhard Rausch. "They ensure vertical safety when, for example, employees have to go into the danger zone for maintenance work or to change the engine." Suspended loads represent a considerable risk and injury potential in machines and systems. If the load drops unintentionally or crashes be brought to a standstill within a very short time.
The backlash-free braking systems brake movements safely and quickly. They clamp with very high rigidity and act directly on the linear guide. This means that they are directly attached to the masses that are to be braked or held. Drive elements between motor and moving mass such as spindle, spindle nut, shaft coupling or gearbox thus have no impact on safety - unlike concepts with engine brake, where all drive elements transmit the braking torque to the slide. In addition, every element between the brake and the slide has a negative effect on the stiffness. The Roba-guidestop are so much stiffer than the often game-afflicted engine brakes and rod or band brakes.
Security through fail-safe principleThe safety brakes work according to the fail-safe principle, ie they are closed when de-energized. Prestressed disc springs press the brake shoes onto the "waist" of the rail, so the rail is clamped. The Roba-guidestop is hydraulically lifted with a nominal pressure of 70 bar. This is relatively low in relation to the very high holding forces. The specialist for safety brakes and clutches has designed the brake mechanism for relatively long stroke distances. This allows the brake compensate for manufacturing tolerances in rails without losing braking power.
The backlash-free clamping of the brake directly onto the profile rail offers even more advantages: The additional stiffening of the NC axis increases the process accuracy and increases the cutting performance. When the axis is stationary, for example during machining, the brake takes over the load. As a result, in this phase, the drive motor can be switched off and taken out of regulation. This eliminates the control movements and thus protects the ball screw.
The closed brake absorbs axial forces. Service life and maintenance intervals are extended. "For us it is important that the design of the brakes is very compact," adds Gerhard Rausch. "Other systems need more space and extra screw-on options. Here, the clamping element is already in the machine, which saves space. "