Safety protection knowledge of the hottest transmi

Safety protection knowledge of transmission equipment

the operation of mechanical equipment depends on power, and the transmission of power depends on the transmission mechanism. The main ways of transmission mechanism include: gear meshing transmission mechanism, belt transmission mechanism, coupling transmission mechanism, etc. Due to the high-speed operation of these mechanisms, a part of the human body may be involved in an unfortunate accident if it contacts, so the protection of transmission equipment has become an important safety issue of mechanical equipment. This paper briefly introduces the dangerous parts of mechanical equipment, the setting and requirements of protective devices of transmission equipment

I. main dangerous parts of common mechanical equipment:

the main equipment commonly used in production are belt conveyors, presses, crushers, mixers, lathes, drilling machines, etc. these equipment usually rely on one or more transmission mechanisms for movement. In the process of movement, there will be overload protection function of dangerous parts, output of experimental reports, energy-saving mode. The manifestations of these dangerous parts mainly include:

1. The bite between rotating parts and tangent moving parts is dangerous parts, such as power transmission belts and pulleys, chains and sprockets, racks and gears, etc

2. Rotating shafts, including connectors, spindles, chucks, lead screws, circular spindles, rods, etc

3. Rotating bosses and holes, such as fan blades, cams, flywheels, etc

4. The bite of opposite rotating parts, such as gears, rolling mills, mixing shafts, round rollers, etc

5. The bite of rotating parts and fixed parts, such as spoke handwheel, machine bed, mixer, etc

6. Approach type, such as hammer body of forging hammer, ram of power press, etc

7. Passing type, such as the workbench and bed of metal planer, the blade of shear machine, etc

8. Unidirectional sliding, such as the teeth at the edge of the band saw, the rim of the grinder, etc

9. Danger between rotating parts and sliding, such as the mechanism on the surface of the lithography machine

if the above dangerous parts are not protected, mechanical injury accidents such as twisting, rolling, collision, extrusion, cutting, impact, entanglement, shearing, stabbing and so on may occur during personnel operation

II. Safety protection measures for commonly used mechanical equipment:

in order to ensure the safe operation of mechanical equipment and the safety of operators, the safety technical measures taken in the safety protection of mechanical equipment can generally be divided into three categories: direct, indirect and guiding

1. Direct safety technical measures are to consider eliminating the unsafe factors of the machine itself when designing the machine, so that people can hardly access the dangerous parts of the machine and realize the intrinsic safety of the machine

2. Indirect safety technical measures are to adopt and install various safe and effective protective devices on mechanical equipment to eliminate unsafe factors in the process of use

3. Guiding safety technical measures are to formulate safety regulations and set signs for machine installation, use and maintenance, so as to prompt or guide the operating procedures, so as to ensure safe operation

to sum up, the risk of mechanical hazards depends on the type, purpose, intrinsic safety protection function of the machine, use method and personnel's knowledge, skills and work attitude; At the same time, it is also related to people's awareness of danger and the skills they have adopted to avoid danger. It is a very important knowledge and skill for post operators to judge what is dangerous nano silver wire, which has small volume, large specific surface area, good chemical and catalytic properties, electrical conductivity, antibacterial properties, physiological compatibility and when danger will occur

III. safety protection of transmission equipment:

1. Protection of meshing transmission. The meshing transmission mechanism must be equipped with a fully enclosed protective device, and no exposed meshing gear is allowed outside the machine, no matter where the meshing gear is located, because even if the meshing gear is located in a place where the operator does not often go, the worker may contact it during the maintenance of the machine and cause unnecessary injury. When designing and manufacturing the machine, try to install the gear into the base without exposing it. For some old equipment, if the meshing gear is found to be exposed, it must be transformed and equipped with a protective cover. The gear transmission mechanism cannot be used without a protective cover

the material of the protective cover can be steel plate or iron wire with metal support. The protective device must be installed firmly and ensure that there is no vibration during the operation of the machine; The device shall be reasonable, the shell of the protective cover shall be consistent with the shape of the transmission mechanism, and it shall be easy to open and maintain the machine, that is, it shall be easy to open and close. In order to attract the attention of workers, the inner wall of the protective cover should be painted red, and it is best to install an electrical interlock to stop the machine when the protective device is turned on. In addition, the protective cover shell itself should not have sharp corners and sharp parts, and try to make it not only not affect the beauty of the machine, but also play a safety role

2. Belt transmission protection. The belt transmission mechanism has the advantages of stable transmission, low noise, simple structure and convenient maintenance. It is widely used in mechanical transmission. However, because the belt is easy to generate electrostatic discharge after friction, it cannot be used in places prone to combustion and explosion

the dangerous parts of the belt transmission mechanism are: the belt joint and the place where the belt enters the pulley, so it should be protected

the distance between the belt protective cover and the belt should not be less than 50mm, and the design should be reasonable without affecting the operation of the machine. Generally, if the transmission mechanism is 2m below the ground, a protective shield should be set. However, in the following three cases, it should be protected even if it is more than 2m; The distance between pulleys is more than 3m; Belt width is more than 15cm; The speed of belt rotation is above 9m/min. In case the belt breaks, it will not fall and hurt people

the joint of the belt must be firm and reliable. The belt shall be installed with proper tightness. The belt transmission mechanism can be protected by covering the belt completely or by protective railings

3. Protection of coupling transmission. The protruding screws, pins, keys, etc. on the coupling may cause injury to workers. Therefore, the safety requirement for the coupling is that there is no protruding part on it, that is, the safety coupling is used. Generally, countersunk screws should be used for the keys and fixing screws on the shaft so that they do not protrude from the shaft surface; But this does not completely eliminate hidden dangers. The fundamental way is to add protective covers, the most common of which is type protective covers

IV. General requirements for safety protection devices of transmission equipment:

1. The safety protection devices shall be simple in structure and reasonable in layout, and shall not have sharp edges and lugs

the Ministry of science and technology has also launched key R & D projects such as the upgrading and industrialization of key basic materials technology, advanced electronic materials and industrialization technology, nano materials and devices, and material genetic engineering. 2. Safety protection devices should have sufficient reliability and sufficient strength, stiffness, stability, corrosion resistance, and fatigue resistance within the specified life span to ensure safety

3. The safety protection device shall be interlocked with the equipment operation to ensure that the equipment cannot operate before the safety protection device does not work; The materials of safety protective covers, screens and barriers and the distance from them to the running parts shall comply with the safety regulations

4. Photoelectric, inductive and other safety protection devices should be equipped with their own failure alarm devices

5. The emergency stop switch shall ensure that all movements of the equipment can be terminated in case of instantaneous action. For equipment with inertia movement, the emergency stop switch shall be interlocked with the brake or clutch to ensure rapid termination of operation

6. The shape of the emergency stop switch should be different from the general switch, and the color is red

7. The layout of the emergency stop switch should ensure that the operator is easy to reach and there is no danger

8. After the equipment is stopped by the emergency stop switch, it must be restarted according to the starting sequence before it can be restarted

v. technical requirements for general mechanical safety facilities, safety devices and safety protective covers:

1 Factors considered in setting and designing safety facilities and safety devices

1) factors considered in setting safety facilities and safety devices

when the design cannot be used to achieve intrinsic safety, safety devices should be used in order to eliminate hazards. Four factors should be considered when setting safety devices:

⑴ strength, stiffness and durability

⑵ impact on the reliability of the machine, such as solid safety devices may overheat the machine

⑶ visibility (from the perspective of operation and safety, it may be necessary to have good visibility of dangerous parts of the machine)

⑷ control other hazards, such as selecting special materials with small linear error to control the total amount of noise

2) factors considered in the design of safety facilities and safety devices

when designing safety devices, human factors should be taken into account. Fatigue is an important factor leading to accidents. Designers should consider the following factors to minimize human fatigue

⑴ correctly arrange various control and operation devices

⑵ correctly select the position and height of the working platform

⑶ provide seats

⑷ it should be convenient to enter and leave the operation site

2. Technical requirements for the safety protective cover of mechanical equipment

1) technical requirements for the safety protective cover of mechanical equipment

⑴ as long as the movable parts that may be touched by the operator cannot operate until the protective cover is closed

⑵ when the fixed protective cover is used, the operator cannot touch the moving parts in operation

⑶ there is enough clearance between the protective cover and the moving parts to avoid any contact between the protective cover and the moving parts

⑷ the protective cover shall be firmly fixed on the equipment or foundation, and tools must be used during disassembly and adjustment. This can not only avoid the impact force when the workpiece flies out, but also extend the time for overhaul and maintenance personnel to confirm the safety of power failure and shutdown of the machine through the action process when removing the protective cover

(5) when the open protective cover is opened or part of it fails, the moving parts shall not operate or the moving parts shall stop moving

⑥ the protective cover used is not allowed to bring new hazards to the production site

⑺ does not affect the operation. It is not necessary to remove the protective cover during normal operation

(8) the protective cover must be firm and reliable to avoid damage caused by contact with moving parts and injury caused by workpiece flying off

⑼ generally, the protective cover is not allowed to step and stand; When it is necessary to make a platform or ladder, it should be able to bear a vertical force of 1500N and take anti-skid measures

2) technical requirements for safety protection of mechanical equipment

the protective cover should adopt a closed structure as far as possible; When the shape structure is required on site, it should meet the provisions of gb8196 1987 "safety requirements for protective covers of mechanical equipment" on the straight-line distance between the safety distance of different eye opening sizes (the outer edge of the protective cover and the space area that may cause injury danger after the human body enters the dangerous area), as shown in the table

safety distance of different eye opening sizes mm