Development of a risk-reduction system for air cylinders

Industrial machinery accidents occupy a quarter of the whole accidents in manufacturing industry, and the ratio is increasing. In these accidents, some of the workers were killed or seriously injured when they were crushed or jammed by industrial machines since these machines have a big power. There are safeguarding equipments such as area sensors and guards at working areas of factories which prevent workers from hazards. Although these equipments are effective in automatic operation of the machines, they are often disabled during adjustment, cleaning, error recovery, or any other maintenance of machines. Many accidents are reported at non-routine work due to a human error when safeguarding was disabled. In order to make workplaces safe, the authors propose a risk-reduction system for air cylinders. The proposed system is attached to the rod end of a typical air-cylinder, and it makes a quick retract when a hand is mechanically detected at the end of the system. The system reduces possible crush risks from an air cylinder without using any external safeguarding system. This paper describes a novel structural principle of the proposed system. The performance of a prototype system is evaluated and the system is proved to be effective in reducing crush risks.