Introduction: the aim of this assignment is to gain general awareness and an understanding of the legal requirements and responsibilities that are involved in the safe working practices associated with robotic assisted manufacture. This is to be achieved by the identification of associated hazards with robotic applications and provide an understanding of how these hazards are overcome.
Typical sources of hazards associated with robotic operations within the working environment include.
Entrapment / entanglement
Process hazards such as toxic fumes, welding flash, lasers, dust, coolant, high-pressure water jet, unguarded abrasive wheel etc. ·
Fire if the robot is function's by use of hydraulics
As a matter of good system design all moving parts of the robot system should by design or enclosure eliminate / minimise all possibilities of the above from happening
The source for theses types of hazards can be caused by
Unknown / unintentional or un-covenanted movements this could be in the form of unpredictable movements whilst the equipment is being maintained or at the reinstatement of power. Other causes may be due to the corruption of software, or damage to the any of the peripherals or programmable electronics. End effecter malfunction, which may result in a component ejection hazard, which can be due to a malfunction of the control system, or programming error. Both of the above may occur as a result of a pneumatic or hydraulic equipment dump fault, as either may have a reservoir and could be subjected to sudden movements of one or more actuators when a jam-up is freed. Hazards may arise from problems when interfacing with other machinery and equipment, especially if the associated machines and equipment are out of programmed sequence with that of the interfacing electronics.
The numerous safety devices that are associated with robotic operations are implemented to only allow access to the robot when the machine's movements have fully stopped and or prevent access to the machine during normal operation thus the possibility of the hazards mention above will be reduced or even eliminated. The devices used to accomplish this include:
Pressure-sensitive mats and floors are devices with a sensitive upper surface so that the pressure applied by a person standing on them will cause dangerous motion to stop. Care should be taken to ensure that access couldn't be gained without actuating the mat.
Interlock are used to allow Access to the enclosure when the robot and associated equipment has fully and prevents it from resuming until the safeguards reinstated
Examples of interlocking devices include:
Guard-operated interlocking devices designed for use in safety systems Key-interlocking devices (trapped key-interlocking) is a common method. In the case of hydraulic and pneumatic equipment, the lock would need to be on a valve actuator. The key cannot be removed from the robot controller (or valve actuator) lock to open the gate lock until a safe condition is established Solenoid locks, this is an electromechanical device activated by an electrical signal. When the signal is received the locking bolt is withdrawn, allowing the access gate to be opened or a second key to be released which in turn releases the gate.
Light Beams and Light curtains
These are the most commonly used sensing devices. They operate by detecting an obstruction in the path taken by a beam or beams of light (a curtain of light). The light may be visible or invisible (infra-red), and may be continuous or modulated (a scanning system).
Light curtains have three basic uses in safeguarding systems:
· as a trip device where the light curtains are usually arranged in a vertical format · as a presence-sensing device where the light curtain is usually arranged in a horizontal format · a combination or zoning system where two or more...
Bibliography: Below are a list of some of the key web sites and documents I used during my research for this assignment.
BS EN 292 Safety of Machinery
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