Machine-Guarding---机械安全防护.ppt

1、Mining and Petroleum Training Service Basics of Equipment Guarding Presented by David Spann Presentation Developed by Rene Azzara,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

2、seem to be as many hazards created by moving machine parts as there are types of machines. 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

3、operation of a machine or accidental contact with it can injure the operator or others 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.TR3,Following an organized and logical

4、 approach, risk assessment and risk reduction can achieve a tolerable risk.,Risk Assessment Process,Gather Equipment Specifications,Identify Equipment Hazards and Task Hazards,Estimate Risk they should be located on or near the machine so the machine can be turned off quickly if a malfunction occurs

5、.,Dangerous moving parts in three basic areas require safeguarding:,Where Mechanical Hazards Occur,Power transmission apparatus All components of the mechanical system which transmit energy to the part of the machine performing the work. These components include flywheels, pulleys, belts, connecting

6、 rods, couplings, cams, spindles, chains, cranks, and gears.,Other moving parts All parts of the machine which move while the machine is working. These can include reciprocating, rotating, and transverse moving parts, as well as feed mechanisms and auxiliary parts of the machine.,1,2,The Point of Op

7、eration The point where work is performed on the material, such as cutting, shaping, boring, or forming of stock.,3,Hazardous Mechanical Motions and Actions The basic types of hazardous mechanical motions and actions are: Motions rotating (including in-running nip points) reciprocating transversing

8、Actions cutting punching shearing bending,Warnings and training are least effective because people will always make mistakes!,Some guards are designed based on hand speed,The 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

9、 and stop the grinder in under 0.03 seconds. T=2(in)/63(in/s)=.032s,Types of guarding devices,Presence Sensing (photo electric light curtain) Pullback - Restraint - Gates or Covers Safety Controls Others: distance and automatic systems,Be Aware of Nip Points: Hazardous spots where loose clothing or

10、body parts could be caught and squeezed in rotating parts. All pulleys, belts, sprockets and chains, flywheels, shafting and shaft projections, gears, and couplings, or other rotating or reciprocating parts.,If it moves, it merits your attention!,Nip Points: Rotating Dangers clothing jewelry hair bo

11、dy parts,Do 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 Permit to Work in a nip point zone. Permit to Work activity must only be undertaken with the mach

12、ine 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 danger! Allow rotating parts to come to a stop before working on them. Use a tapered punch

13、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, liquids, or solids with hands. Reflex damage can occur immediately. Keep grinder tool rests adju

14、sted 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 operation. If guards are removed to perform maintenance, replace immediately after servicing.,

15、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 straight, continuous line) creates a hazard because a worker may be struck or caught in a pinc

16、h or shear point by the moving part.,More Safety Considerations Never step across a rotating power shaft. Equipment operators should wear close-fitting clothes and slip-resistant footwear. Rotating parts catch loose clothing easily. Never allow children around the equipment or work area.,LOTO - Lock

17、out/Tagout (aka) CHE - Control of Hazardous Energy,Machinery Maintenance and Repair Good maintenance and repair procedures contribute significantly to the safety of the maintenance crew as well as that of machine operators. In addition to guarding, you need to understand:,In shops where several main

18、tenance 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 general policy, lockout control is gained by the procedure of issuing personal padlocks

19、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 employees performing the servicing or maintenance which are unique to the repair or m

20、aintenanceprocedures 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 machine can still be hazardous due to the possibility of the machine becoming reenergize

21、d 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 the machine cannot cycle or be started until the guard is back in place. Adjustable -

22、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 offer different degrees of protection.,Guards Guards are barriers which prevent acce

23、ss 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. However, not all machines in use have built-in safeguards provided by the manufacturer!

24、,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 additional functional purposes.,Be wary of older equipment! Inspect older equipment, an

25、d 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 them. Guard pinch points on conveyor pulleys Establish and enforce policies that pro

26、hibit 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.,User-built guards are sometimes necessary for a variety of reasons. They have t

27、hese 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 individual motor drives. They permit options for point-of-operation safeguards w

28、hen 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 safeguards by plant personnel can help to promote safety consciousness in the wor

29、kplace.,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 to be installed at some point, yet never were.,?,Additional considerations when

30、 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 awareness of a hazard, administrative controls or procedures such as war

31、nings, 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 fail, will the whipping action of broken belts be contained? Is the guar

32、d 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 and replace easily. Design Considerations: Lightweight, without being flimsy Can

33、be handled by one person Access doors or tops Guards with rollers or wheels Screen that allows operator visual access; also allows operator to rinse off machinery Design so hands and tools cannot fit thru screen,Machine Safety Responsibilities,Management Ensure all machinery is properly guarded Supe

34、rvisors Train employees on specific guard rules in their areas; Ensure machine guards remain in place and are functional; Immediately correct machine guard deficiencies Employees Do not remove guards unless machine is locked and tagged; Report machine guard problems to supervisors immediately; Do no

35、t operate equipment unless guards are in place,Proper training should address:,Hazards associated with particular machines How the safeguards provide protection and the hazards for which they are intended How and why to use the safeguards How and when safeguards can be removed and by whom What to do

36、 if a safeguard is damaged, missing, or unable to provide adequate protection,Deaths attributed to Inadequate Guarding from MSHA files,On July 21, 2005, a 31-year old plant operator with two years mining experience was fatally injured at a sand and gravel operation. The victim made a splice on a con

37、veyor 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 a rock crushing machine. The victims job

38、 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 victim was caught by one of the rock crushi

39、ng 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 surrounds the entire machines perimeter

40、 instead of intermittently placed push buttons.,What steps did the investigator note that should have been taken that would have prevented this fatality?,Trip cable accessible to operator,No,No,No,Yes,An effective guard is required,Does the idler present a significant hazard? Is a person likely to g

41、et close to the idler roller face? Is the nip point directly accessible?,Yes,Yes,On 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 to

42、ggle seat 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 stee

43、l bar to 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.,Deadly Force Impact,On November 23, 2003, a 44-y

44、ear-old company vice president with 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 remo

45、ve jammed material while machinery 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 sho

46、uld be designed and installed where 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

47、 falling into the hopper. In order to 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

48、in and crushed between the head sprocket 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 locking out. His pant legs also hung down below his boots.,Lesson: Follow task proc