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Summary Of Fatal Accident Of Mechanical Arm Injury

Summary Of Fatal Accident Of Mechanical Arm Injury

Oct 08, 2020

On June 6, 2019, 5 in the morning when 29 points, a smeltery zinc ingot casting process 307 class palletizing line main operating mechanical arm hand jin mou in automatic code spindle units without downtime, never closed police exit into the area of automated code ingot machine, mechanical arm in the field of health were working radius, walk to code in ingot ingot machine position and mechanical arm range, by the top spindle device receives the water-cooled chain transmission over zinc ingot, signal transmission to the mechanical arm, automatic mechanical arm rotating spindle, instant will be jin toppled in the top spindle device, zinc ingot grab clamp squeezing in jin mou left chest.

According to relevant reports, one third of the world's production accidents are mechanical safety accidents. If you open the Pandora's box of accidents, it is not difficult to find that the reasons for safety accidents in machining can be completely simplified as: personnel exposure and equipment failure.


Although however in this case, the enterprise has clear stipulation "forbidden space in mechanical arm operations into the operational areas", "after power mechanical arm, the operator can enter the homework radius", but it also makes the mechanical risk protection needed to follow the principle of one of the principle of isolation to stop, only rely on administrative measures for control and actual safety protection facilities is not perfect, the fence door interlock with mechanical arm is not effective, the operator is so was exposed to danger......

Hypothesis: a safety lock switch is installed on the safety protection door

The safety gate switch is composed of two independent parts: the switch body and the switch operator. When the safety protection door is opened, the switch operator is pulled from the switch body and the normally closed contact in the switch is disconnected by a mechanical rebound device. Once the actuator is pulled out of the body, the controller immediately cuts off the power source to stop the movement of the interior parts of the protective barrier.


In the above accident, if the safety lock switch is installed on the safety gate of the fence, then as soon as Kim opens the safety gate of the fence, the mechanical arm will be cut off and stop operation. Coupled with the program of Lock out Tag out, it can ensure that the mechanical arm is always in power off state after Jin enters the protective fence, which not only conforms to the relevant regulations of the enterprise, but also ensures its own safety.

Assumption: Safety carpet is laid within the operating radius of the manipulator

Safety carpet (pad) is a pressure-sensitive safety protection device. When a set minimum weight is applied to the safety carpet, the switch will be off and the controller will send a stop signal to the protected machine to stop its movement. Reliability protects the operator from a variety of potential hazards.


In the above accident, if the safety carpet is laid within the working radius of the mechanical arm (a certain safe distance should be reserved), the controller can make the mechanical arm enter the power off state once Jin steps into the dangerous area, to protect the safety of personnel.


The international standard ISO 14120 defines requirements for the design of mechanical fences and ISO 13857 specifies the safe distance and pore size between fences and hazardous equipment to prevent people from crossing and crossing fences.

image

The figure above simulates high risk actions, with 1 representing the danger point, 2 representing the ground and 3 representing the security fence.

A is the height from the hazard point to the standing surface, B is the height of the fence, and C is the horizontal distance of the operator from the hazard point.