加工中心机械安全防护HP1.ppt

Some pinch points are not so obvious. Note the hand wheel. Ask class: What would happen to your fingers if they were gripped around the hand wheel and you began to turn the wheel? (fingers caught between wheel spokes and table). Ask class: How could this hazard be fixed? (move wheel farther from table, and/or make the hand wheel solid - no spokes). Screw conveyors have pinch points that travel along the conveyor pan. Grinding wheels have pinch points where the wheel and the tool rest come together. Ask class: Does anyone know what the distance between the grinding wheel and the tool rest should be? (1/8 of an inch - grinding wheels only - other pinch points must be guarded if the gap between parts creating the pinch point is 1/4 inch or more) * A wide variety of basic mechanical motions and actions can present hazards to the worker. Recognizing these motions and actions is an important first step toward protecting employees from the dangers they may present. Rotating motion. Injuries resulting from contact with rotating parts can be severe. Even smooth, slowly rotating shafts can grip clothing, and through skin contact, force an arm or hand into a dangerous position. Collars, couplings, cams, clutches, flywheels, shaft ends, spindles, and horizontal or vertical shafting are some examples of common rotating mechanisms that may be hazardous. There is added danger when bolts, nicks, abrasions, and projecting keys or set screws are exposed on rotating parts of machinery. In-running nip point hazards are caused by the rotating parts on machinery. A nip is “to catch hold of and squeeze tightly between two surfaces, edges, or points.” There are three main types of in-running nips on rotating parts: Parts with parallel axes that rotate in opposite directions (i.e., as with intermeshing gears, rolling mills, calendars). Rotating and tangentially moving parts (e.g., the point of contact between a power transmission belt and its pulley). Rotating and fixed parts tha