Safety Equipment for Robotic Welding
Industrial welding has always been known as a hazardous job. Automating welding applications with robotic welding systems has reduced the safety risks once imposed on workers. In today’s industrial settings welding robots have become commonplace with more than half of all robots in North American being used for arc welding and automated spot welding applications.
While automating with industrial robots helps to reduce the safety hazards associated with welding for workers, it is important to ensure proper safeguards and safety equipment are put in place. Safety equipment protects floor workers while operating a robotic welding system. Common safety equipment used for robotic welding includes interlocked perimeter guards, safety light curtains, laser scanners, and pressure sensitive mats. Installing these devices provides an effective strategy for preventing potential adverse incidents to keep your factory floor as safe as possible.
Interlocked perimeter guards are designed to close off the work area of a welding robot in order to keep employees away while it is operating. Barriers surround the robot’s work envelope and makeup the walls of a robotic workcell. One or two walls of the workcell will consist of interlocking doors or gates. The interlocking gates are synchronized to the robotic power source to ensure that when a gate is open, power to the robot is turned off. If the door to a Motoman Arcworld weld cell suddenly was to open, the Motoman MA1400 operating inside would automatically stop welding, protecting surrounding workers. The interlock switch of the gate is responsible for shutting down the power supply. Some interlock switches contain a locking device that will keep the barrier gate closed until the work area is safe. Installing proper safety barriers around a robotic welding system is an OSHA requirement.
Safety light curtains incorporate infrared light beams to detect the intrusion of a person or object within a robotic workcell. Light curtains are usually used when operators require frequent access to the workcell as they can stop a six axis robot’s operation relatively quickly. A transmitter is used to emit the light beam to a receiver. How these devices are installed will determine the projection field, which can either be vertical or horizontal. When the projection field is crossed by a person or object, a stop signal is generated to the robot control. Light curtains do allow for flexibility for operations requiring material feeding since they can be programmed to respond to objects of certain defined sizes. This is a very important aspect to welding automation. This allows for parts to be continuously fed to a FANUC Arcmate 120ic without tripping the light curtains and disrupting welding.
Laser scanners use laser light to guard weld cells. These devices scan surroundings and measure distances for intruders. If a person or object come into contact with the scanner, the articulated robot will be signaled to stop welding. Some scanners may allow for warning zones in which a warning is sent out first to prevent an operator from entering a workcell without having to stop the robot.
Pressure sensitive safety mats may be installed as a secondary safety device to ensure robotic welding equipment stops operation should an operator enter the workcell. They are typically placed inside the interlocked door or gate so that when a person steps on the mate a signal is sent to the controller. The robot will automatically stop operation or be prevented from resuming welding.
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