Actuated by physical contact, tactile safety monitoring devices stop the hazardous movement. The diversity of applications requires constructively different devices.
The safety edges of the SE range are suitable for safe-guarding crushing and shearing points, that can be present on guards, lifting tables and platforms, mobile storage shelving, operating process tables, storage lifts, lift doors, loading ramps, lifting and tilting devices or industrial gates. They immediately stop the dangerous movement, thus preventing physical injury or material damage. The safety flaps of the SL 300 range are designed for the protection of man and machine at machines with wide material input or feed areas. The safety mats of the SMS 3 range are used to protect surfaces in danger zones on machines and plants with dangerous movements. Depending on the shape of the area to be protected, multiple safety mats can be laid in line and electrically connected. When the safety mat is actuated, a signal is evaluated and the machine stop is initiated.
In combination with a suitable connected safety monitoring module, the three above-described systems achieve control category 3 respectively 1 or 4 to EN 954-1.
Design and mode of operation:
The SE range safety edges consist of 3 basis elements, i.e. an aluminium profile, a rubber profile and a pair of plug-in sensors. The deformation of the rubber profile of the safety edge is evaluated. The basic element is a fail-safe transmitter/receiver unit in both extremities of the rubber profile. The deformation of the rubber profile reduces or interrupts the IR signal between the transmitter and the receiver. The connected safety monitoring module evaluates the reduction of the IR signal and stops the hazardous movement. This measurement procedure, i.e. in conjunction with a connected safety monitoring module, complies with the safety requirements of control category 4 to EN 954-1. Solutions for applications of category 1 are also available. EN 1760-2 resumes the requirements for safety edges and describes their design and homologation. Safety-relevant properties such as operating-temperature range, response times, efforts, just-operate travels and over-travels are defined in this norm as well. EN 954-1 describes the guidelines for the design of safety-related components of the machine control. The risk when using a local machine or unit must be determined. The higher the risk, the more severe the safety requirements for the control. The safety edge system of the SE range with a connected safety monitoring module of the SE-400 C range complies with the safety requirements of control category 4. Even if there are 2 errors in the system, the safety edge will ensure a safe and efficient standstill of the machine or unit. For applications of control category 1 to EN 954-1 the SE range safety edge can be connected to a safety monitoring module of the SE-100 C range. When using a safety edge, it must be ensured that the speed of the hazardous movement is lower than the maximum starting speed of the safety edge. The stopping distance of the dangerous components and the specific profile data must be adapted to one another. On the one hand, the stopping distance must be sufficient to stop the machine in the worst case and on the other hand the effort exercised on the threatened parts of the body may not exceed the maximum limit. During the planning, attention must be paid to the execution of the opposite sides. If the over-travel of the chosen safety edge is insufficient, then either the stopping distance of the machine is to be reduced either using another model should be considered. The required minimum over-travel must be calculated with a safety factor of at least 1,2. The safety coefficient must be increased if the over-travel is influenced by other machine elements (also refer to EN1760-2 Annex C). SL 300 safety flaps consist of a flap and carrier profile and a position switch class 1. The actuation of the flap profile causes a positive break of the position switch, thus switching off the corresponding machine drive. SMS 3 safety mats include 2 separate currentcarrying steel plates. The plates are held apart by insulating strips. The construction is moulded in Plastisol, a mechanically robust plastic that is highly resistant to chemicals. Upon actuation of the safety mat, the inner steel plates are slightly bent, causing an electrical short-circuit. This signal is evaluated by a connected safety monitoring module, which immediately initiates the machine shutdown.
Schmersal Safety-related Tactile Sensors Catalog Pages in *.pdf format