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1、Machine-Guarding-Machine-Guarding-机机械安全防护械安全防护Basics of Machine Safeguarding Crushed hands and arms, severed fingers, blindness -the list of possible machinery-related injuries is as long as it is horrifying. There seem to be as many hazards created by moving machine parts as there are types of mach
2、ines. Safeguards are essential for protecting workers from needless and preventable injuries. A good rule to remember is: Any machine part, function, or process which many cause injury must be safeguarded. When the operation of a machine or accidental contact with it can injure the operator or other
3、s in the vicinity, the hazards must be either controlled or eliminated.Tolerable Risk:risk that is accepted for a given task and hazard combination- as described in ANSI B11.TR3Following an organized and logical approach, risk assessment and risk reduction can achieve a tolerable risk.Risk Assessmen
4、t ProcessGather EquipmentSpecificationsIdentify EquipmentHazards and Task HazardsEstimate Risk& ProbabilityDetermine Whether RiskIs TolerableDetermine Equipment LimitationsUse LimitationsSpace LimitationsTime LimitationsEnvironment LimitationsInterface LimitationsVery Likely to OccurLikely, May Occu
5、rUnlikely, Not Likely to OccurRemote: Very UnlikelyCatastrophic: Permanent DisablingSerious: Severe DisablingModerate: Significant DisablingMinor: Sligh DisablingIf Untolerable,Risk Reduction MeasuresMust Be ImplementedUse PPEIncorporateAdministrative ControlsIncorporateSafeguarding TechnologiesElim
6、inate and ReduceHazards by DesignSupportivePrimaryHazard Reduction ActivitiesWhere to begin Know how to use the machine safely before operating. Have you reviewed the owners manual? It will provide operating, repairing, lubricating and fuel information. Are the Warning Decals in place? Are the machi
7、ne guards properly placed and in good condition? Are electrical lines damage free? Are air and hydraulic lines in good condition and not leaking? Is the setup a proper setup? Is the area around the machines orderly? Safety begins before you even start the equipment!Personal Protection: Wear PPE, suc
8、h as goggles, safety shoes and leather gloves. Long hair should be tied back or tucked under to avoid getting caught in machinery. Avoid wearing jewelry. Machine Maintenance Checklist for Safety: Keep machines repaired, lubricated and adjusted. Clean up excess lubricants. Clearly mark control switch
9、es and valves that control machines. Check machines for emergency stop switches; they should be located on or near the machine so the machine can be turned off quickly if a malfunction occurs. Dangerous moving parts in three basic areas require safeguarding:Power transmission apparatus All component
10、s of the mechanical system which transmit energyto the part of the machine performing the work. These components include flywheels, pulleys, belts, connecting rods, couplings, cams, spindles, chains, cranks, and gears. Other moving partsAll parts of the machine which move while the machine is workin
11、g. These can include reciprocating, rotating, and transverse moving parts, as well as feed mechanisms and auxiliary parts of the machine.The Point of OperationThe point where work is performed on the material, such as cutting, shaping, boring, or forming of stock.Hazardous Mechanical Motions and Act
12、ions The basic types of hazardous mechanical motions and actions are: Motions rotating (including in-running nip points) reciprocating transversing Actions cutting punching shearing bending Warnings and training are least effective because people will always make mistakes!Some guards are designed ba
13、sed on hand speedThe human hand can move at 63 inches per second!Example: A device located 2 inches from a grinder must be able to sense the hand and stop the grinder in under 0.03 seconds. T=2(in)/63(in/s)=.032sTypes of guarding devicesPresence Sensing (photo electric light curtain)Pullback - Restr
14、aint - Gates or CoversSafety ControlsOthers: distance and automatic systemsBe Aware of Nip Points:Hazardous spots where loose clothing or body parts could be caught and squeezed in rotating parts.All pulleys, belts, sprockets and chains, flywheels, shaftingand shaft projections, gears, and couplings
15、, or other rotating or reciprocating parts.Nip Points:Rotating Dangers clothing jewelry hair body partsDo not wear gloves around reciprocating or rotating machine parts. Note: A nip point entry permit system is intended for observation of hazardous machinery while at a safe distance.It is not a Perm
16、it to Work in a nip point zone. Permit to Work activity must only be undertaken with the machine shut down and locked out.Protecting Hands and Fingers Guide: Identify the pinch points on mechanically moved loads, lowered loads and metal drums. Know when to wear gloves. Sometimes gloves can present a
17、 danger! Allow rotating parts to come to a stop before working on them. Use a tapered punch or other appropriate tool to align the holes in parts. Rings should not be worn when operating or repairing machinery. Remove fuses with fuse removers, not fingers. Do not test the temperatures of gases, liqu
18、ids, or solids with hands. Reflex damage can occur immediately. Keep grinder tool rests adjusted to 1/8 inch gap or less. Handle sharp or pointed tools (hatchets, chisels, punches, awls, knives, pitch forks and machine blades) carefully. Perform maintenance only when tools or machinery are not in op
19、eration. If guards are removed to perform maintenance, replace immediately after servicing. Reciprocating motions may be hazardous because, during the back-and-forth or up-and-down motion, a worker may be struck by or caught between a moving and a stationary part.Transverse motion (movement in a str
20、aight, continuous line) creates a hazard because a worker may be struck or caught in a pinch or shear point by the moving part.More Safety ConsiderationsNever step across a rotating power shaft.Equipment operators should wear close-fitting clothes and slip-resistant footwear. Rotating parts catch lo
21、ose clothing easily. Never allow children around the equipment or work area. LOTO - Lockout/Tagout (aka)CHE - Control of Hazardous EnergyMachinery Maintenance and Repair Good maintenance and repair procedures contribute significantly to the safety of the maintenance crew as well as that of machine o
22、perators. In addition to guarding, you need to understand:In shops where several maintenance persons might be working on the same machine, multiple lockout devices accommodating several padlocks are used. The machine cannot be reactivated until each person removes his or her lock. As a matter of gen
23、eral policy, lockout control is gained by the procedure of issuing personal padlocks to each maintenance or repair person; no one but that person can remove the padlock, thereby each worker controls the power systems. Whenever machines or equipment are serviced, there are hazards encountered by the
24、employees performing the servicing or maintenance which are unique to the repair or maintenanceprocedures being conducted. These hazards may exist due to the failure of the employees doing the servicing or maintenance to stop the machine being worked on. Even if the machine has been stopped, the mac
25、hine can still be hazardous due to the possibility of the machine becoming reenergized or restarting. Fixed - A fixed guard is a permanent part of the machine.Interlocked - When this type of guard is opened or removed, the tripping mechanism and/or power automatically shuts off or disengages, and th
26、e machine cannot cycle or be started until the guard is back in place. Adjustable - Adjustable guards are useful because they allow flexibility in accommodating various sizes of stock. Self-Adjusting - The openings of these barriers are determined by the movement of the stock. Self-adjusting guards
27、offer different degrees of protection. Guards Guards are barriers which prevent access to dangerous areas. There are four general types of guards: Guard Construction Today many builders of single-purpose machines provide point-of-operation and power transmission safeguards as standard equipment. How
28、ever, not all machines in use have built-in safeguards provided by the manufacturer! Guards designed and installed by the builder offer two main advantages: They usually conform to the design and function of the machine. They can be designed to strengthen the machine in some way or to serve some add
29、itional functional purposes. Be wary of older equipment!Inspect older equipment, and if necessary upgrade machinery to current standards.Lock out or block moving machinery against motion before working nearby unless all pulleys and pinch points are guarded or located where persons can not contact th
30、em.Guard pinch points on conveyor pulleys Establish and enforce policies thatprohibit work or travel near unguarded machinery components.A conveyor attendant with 5 years mining experience was fatally injured at an open pit copper operation. The victim became entangled in a tripper conveyor pulley.U
31、ser-built guards are sometimes necessary for a variety of reasons. They have these advantages: Often, with older machinery, they are the only practical safeguarding solution. They may be the only choice for mechanical power transmission apparatus in older plants, where machinery is not powered by in
32、dividual motor drives. They permit options for point-of-operation safeguards when skilled personnel design and make them. They can be designed and built to fit unique and even changing situations. They can be installed on individual dies and feeding mechanisms. Design and installation of machine saf
33、eguards by plant personnel can help to promote safety consciousness in the workplace. User-built guards also have disadvantages: User-built guards may not conform well to the configuration and function of the machine. There is a risk that user-built guards may be poorly designed or built. Intended t
34、o be installed at some point, yet never were.Additional considerations when building a guard:Does the design, construction, selection of materials and guard installation prevent contact with all moving machine part hazards?Does the guard provide protection by itself,and not rely on visual or tactile
35、 awareness of a hazard, administrative controls or procedures such as warnings, signs, lights, training, supervision or PPE?Are the guard materials, fastening methods, and construction suitable to withstand the wear, corrosion, vibration and shock of normal operations?If drive belts inside a guard f
36、ail, will the whipping action of broken belts be contained?Is the guard recognizable as a guard?Is the guard installed securely?Ergonomic Considerations of Machine Safeguarding Consider worker stress and fatigue when designing.Employees may defeat guarding if it is difficult to remove andreplace eas
37、ily.Design Considerations:Lightweight, without being flimsyCan be handled by one personAccess doors or topsGuards with rollers or wheelsScreen that allows operator visual access; also allows operator to rinse off machineryDesign so hands and tools cannot fit thru screenMachine Safety Responsibilitie
38、sManagementEnsure all machinery is properly guardedSupervisorsTrain employees on specific guard rules intheir areas; Ensure machine guardsremain in place and are functional;Immediately correct machine guard deficienciesEmployeesDo not remove guards unless machine is locked and tagged; Report machine
39、 guard problems to supervisors immediately; Do not operate equipment unless guards are in placeProper training should address: Hazards associated with particular machinesHow the safeguards provide protection and the hazards for which they are intendedHow and why to use the safeguards How and when sa
40、feguards can be removed and by whom What to do if a safeguard is damaged, missing, or unable to provide adequate protectionDeaths attributed toInadequate Guardingfrom MSHA filesOn July 21, 2005, a 31-year old plant operator with two years miningexperience was fatally injured at a sand and gravel ope
41、ration. The victim made a splice on a conveyor belt and was making adjustments to the belt.He was found entangled in the tail pulley of the conveyor. On February 7, 2002, a 37-year-old male laborer (the victim) was fatally injured when he became caught between a conveyor belt and an idler pulley of
42、a rock crushing machine.The victims job consisted of sweeping and shoveling the area around the rock-crushing machine. Approximately 20 minutes after the victim arrived at work he was found underneath the rock crushing machine with his arm caught between a conveyor belt and an idler pulley. The vict
43、im was caught by one of the rock crushing machines conveyor belts and an idler pulley. The location of the victim was underneath the machine near the electrical panel. Hazard analysis of equipment prior to use. Employee task training. Proper guarding. Installation of pull cable emergency stops that
44、surrounds the entire machines perimeter instead of intermittently placed push buttons.What steps did the investigator note that should have been taken that would haveprevented this fatality?NoNoNoYesAn effective guard is requiredDoes the idler present a significant hazard?Is a person likely to get c
45、lose to the idler roller face?Is the nip point directly accessible?YesYesOn June 17, 2005, a 32-year-old equipment operator/mechanic with 5 years mining experience was fatally injured at a sand and gravel operation. The victim was removing toggle seat wedge bolts so that the broken pitman toggle sea
46、t could be replaced. The safety pins, provided by the manufacturer: - had not been installed - no steps had been taken to block/secure this component against hazardous motion. The pitman assembly shifted and fatally pinned the victim against the crusher framework. The victim was using a steel bar to
47、 dislodge a blockage in an impact crusher. The bar contacted a moving crusher component causing it to be propelled and strike the victims neck. The accident occurred because the procedures used to dislodge the blockage of rock were inadequate. On November 23, 2003, a 44-year-old company vice preside
48、ntwith 2 years mining experience was fatally injured at a crushed stone operation. When the blockage occurred, the victim failed to deenergize and lock out the crusher before attempting to dislodge the rock. Lesson: Deenergize and lockout equipment.Never attempt to remove jammed material while machi
49、nery is in operation. Shut down, isolate, and block all forms of hazardous energy before performing machine maintenance.Do not allow employees to position themselves directly over the intake of a horizontal impactor while it is actively crushing rock.Viewing decks should be designed and installed wh
50、ere workers can safely access the equipment to observe operation.Nothing can protect you from senseless acts.The worker had reversed his truck up to the primary hopper in order to discharge a load of quarried material.He then walked to the rear of his truck, before falling into the hopper.In order t
51、o discharge the load, it was not necessary to leave the truck. It is unknown why the driver did so.Lock out before servicing As he was oiling a moving conveyor, a workers pant leg became entangled in the part of the conveyor, causing his right foot to be dragged in and crushed between the head sproc
52、ket and the side of the conveyor. His right leg had to be amputated below his knee. The worker usually oiled the conveyor from a relatively safe position from underneath the conveyor. For some reason, on this day, he decided to oil the conveyor from an unstable position above the conveyor without lo
53、cking out. His pant legs also hung down below his boots. Lesson: Follow task procedures every time!Work safely around guardrails A machine tender was found pinned in the ingoing nip point of a press. He died from massive crush injuries. There was no witness to this accident. Guardrails were in place
54、 around the machine.It is unclear how the victim fell into the nip point of the press.He may have been reaching into or over top of one of the guardrails. Lesson: Never reach through or over top of a guardrail ofany machinery. Safe work practices: Do not defeat guards and place bodyparts, tools or p
55、ry bars in equipmentthat is not deenergized or LOTO.Develop and follow written procedures for checking the well-being of a worker working alone or in isolation, including establishingcontact at predetermined intervals and at the end of the shift. Ensure that miners receive task training prior to all
56、owing them to perform maintenance or repair on machinery or equipment.Discuss the work procedures, including all possible hazards ( Risk Assessment ) and ensure the manufacturers recommendations are followed for all repair work.Before working on equipment, lock-out the power and block equipment comp
57、onents against all possible motion/movement resulting from a sudden release of energy.Make sure you have the proper AUTHORITY to deenergize or lock-out equipment before proceeding. Shutting off power may shut down production in other areas and create safety hazards to unsuspecting individuals.If potential hazards or prescribed procedures are unclear, DO NOT proceed until all safety concerns are adequately resolved.Now we will watch the DVD:结束结束
