Thread Content
I. Classification of lubrication methods: Classification of lubrication systems: throttle type, single-line type, double-line type, multi-line type, progressive type, oil mist type, manual, semi-automatic, automatic, continuous, intermittent, etc. II. Selection of Lubrication Method 1. Factors to Consider When Selecting a Lubrication Method (1) The number and characteristics of the lubrication points in the equipment. (2) The operating environment of the equipment. (3) Types and quantities of lubricants used for the equipment. (4) Is the structure of the equipment conducive to circulating lubrication? (5) Requirements for the degree of automation in equipment lubrication. (6) The device has good sealing performance, with no leaks and no environmental pollution. (7) Other requirements besides equipment lubrication. Such as cooling, braking, and hydraulic transmission. Choosing the lubrication method is an issue to consider when designing and manufacturing equipment, and improvements to the lubrication systems of existing equipment also need to be taken into account. 2. Standardization of lubrication systems: The GB6576 standard \"Lubrication Systems for Machine Tools\" specifies the requirements for lubrication systems in metal cutting machine tools and other types of general machinery, with reference to relevant international ISO standards. It specifies the technical requirements for relevant components, as well as the general requirements for the design, operation, and maintenance of the system. It contributes to the standardization of mechanical equipment lubrication systems, facilitating their use and maintenance. III. Selection of Lubrication Devices 1. General requirements of equipment for lubrication devices (1) It must be capable of lubricating all friction pairs in the equipment. (2) The amount of lubricant supplied is easy to adjust. (3) Mechanize the lubrication system as much as possible to reduce manual operation. (4) Achieve automation of the lubrication system as much as possible, with good performance and reliable operation. (5) The structure of the device should be as simple as possible to facilitate maintenance and repair. (6) Consider the recycling of lubricants. (7) The device has good sealing performance, does not leak, and does not pollute the environment. 2. Selection of lubrication devices (1) Manual oiling lubrication device The manual oiling lubrication device has a simple structure. It is mainly used in the distributed lubrication areas of general mechanical equipment. Manual oiling for lubrication results in low utilization of the lubricant. It is generally used for lubricating low-load, low-speed friction pairs. Common manual oiling lubrication devices have been standardized. (2) Centralized lubrication system: The centralized lubrication system is mainly used in lubrication systems with a large number of lubrication points on equipment, and it comes in two forms: intermittent lubrication and continuous lubrication. Centralized lubrication reduces the manual labor of operators and improves the reliability of lubrication. Depending on the lubricant used, there are centralized lubrication systems with thin oil and those with dry oil. The lubrication systems vary depending on the equipment, but the main components of these systems have been largely standardized, which facilitates the maintenance of the equipment’s lubrication systems. IV. Principles and Applications of Common Lubrication Methods and Devices 1. Principles and Applications of Light Oil Lubrication Methods and Devices Lubrication using lubricating oil is known as light oil lubrication. Thin oil lubrication has the following characteristics: (1) It has a flushing and cooling effect. It can remove the wear debris and heat generated at the friction areas, thereby reducing abrasive wear and adhesion. (2) Easy to replace – lubricant can be changed conveniently without having to disassemble the machinery. (3) Facilitates centralized lubrication and circulating lubrication to ensure optimal lubrication conditions for the equipment. (4) Used oil can be recycled and reused to protect the environment. 2. Principles, applications of dry oil lubrication methods and devices. Grease lubrication is also known as dry oil lubrication or thick oil lubrication. The characteristics of dry oil lubrication are: (1) it is suitable for friction pairs under high pressure and high temperature. (2) Suitable for lubricating machinery subjected to variable loads and shocks. (3) It has a simple structure and provides sealing functionality. (4) Suitable for the lubrication requirements under special conditions such as radiation, centrifugation, and weightlessness. 3. Management and improvement of lubrication systems Lubrication components and systems are important parts of equipment, and they constitute the fundamental elements for ensuring proper lubrication of the equipment. The units and personnel using the equipment must, in accordance with the requirements for equipment management, properly maintain, utilize, and service the lubrication systems to ensure adequate lubrication of the equipment. The requirements are as follows: (1) The operators of the equipment must use and take care of the lubrication systems properly, and avoid rough or aggressive handling to prevent damage to these systems. (2) Spare parts should be kept in stock for standard lubrication components. Once damage or failure is detected, it must be replaced immediately to ensure proper lubrication of the equipment. (3) The wear-prone components of the lubrication systems in imported equipment must be mapped out to manufacture the necessary spare parts. (4) The equipment lubrication devices and systems should be inspected regularly. Confirm that the lubrication device is in good condition and that the oil pathways in the lubrication system are unobstructed. 4. Principles for improving lubrication systems When the existing lubrication system is unable to ensure proper lubrication of the equipment, improvements should be made. The principles for such improvements are: (1) Improve the lubrication condition of the equipment and address any issues with lubrication resulting from design or manufacturing defects. (2) Reduce the workload of manual refueling and avoid equipment lubrication failures caused by human factors. (3) The original lubrication device is damaged; a lubrication device with better performance has been replaced. (4) Improvement in the performance of lubrication systems. Replace the device’s original lubrication system with a high-performance one. 5. Methods for improving lubrication systems (1) Changing from distributed lubrication to centralized lubrication. Various types of centralized lubrication systems are available on the market today. It can be used both for the production of mechanical equipment and for the renovation of older models of equipment. Among these devices, there are mechanical and electronic controls, which are highly beneficial for replacing manual lubrication with automatic lubrication at the fueling stations. Especially for conventional metal cutting machines, the use of an intermittent centralized oil supply device enables timed and quantitative centralized oil supply to multiple lubrication points on the machine. It helps to reduce the workload associated with manual refueling and improve the lubrication condition of the equipment. Centralized light oil lubrication systems used to switch from manual lubrication to timed lubrication in fully loss systems; products from companies such as Juyuan Lubrication Parts Factory in Xieshan County, Ningbo Sanlang Lubrication Components Co., Ltd., Anyang Lubrication Equipment Factory, and Nanjing Bechel Company are available. (2) Install a status monitoring and display system for the lubrication system; by using pressure sensors, temperature sensors, as well as display and signaling systems, it is possible to achieve alerts for low voltage, high pressure, or high temperature in the lubrication devices and systems. It prevents equipment failures caused by operators failing to detect lubrication problems in a timely manner. (3) An intelligent lubrication condition monitoring system is used to achieve online, continuous monitoring of the lubrication and wear conditions of critical equipment. The products include oil mist detectors, display-type ferrography analyzers, etc. V. Leakage and Sealing Technologies for Lubrication Systems 1. Oil Leakage in Equipment and Its Remediation Oil leakage in equipment is a common defect in lubrication and hydraulic systems. Oil leakage can lead to poor lubrication of the equipment, affecting its performance ； Oil leakage also leads to waste of oil, which not only pollutes the environment but also affects the economic efficiency of enterprises. 2. Causes of oil leakage (1) Design-related reasons: unreasonable and imperfect structure. (2) Manufacturing-related reasons: low processing precision, and quality defects in the parts. For example, a non-through hole is processed into a through hole. (3) Reasons related to repairs: Parts were damaged during repairs ； Missing sealing parts ； Reasons such as the absence of sealant and loose fasteners. (4) Reasons related to components and materials: aging and failure of sealing components, or viscosity of lubricating materials being lower than the required level, etc. 3. Evaluation criteria for equipment oil leakage: (1) Oil seepage: When oil stains are not visible and no such stains appear within 5 minutes after wiping, it is considered oil seepage. (2) Oil leakage: Visible oil stains or oil droplets. If oil stains or droplets reappear within 5 minutes after cleaning, it is considered oil leakage. (3) Oil leakage point: A location with a visible oil stain or an oil droplet is considered an oil leakage point. (4) Oil-free equipment: Equipment is considered oil-free if there is no oil leakage from the static mating surfaces and no oil seepage from the dynamic mating surfaces. A device is considered to be basically leak-free if more than 80% of its joint surfaces do not leak oil, and no more than one drop of oil leaks from any leaking area within 3 minutes. (5) Equipment with severe oil leakage: daily oil consumption of 1 kg or more, or a total of 3 drops or more of oil dripping from all leakage points within 1 minute. (6) General oil leakage equipment: There is oil leakage, but it does not reach the level of severe oil leakage equipment. (7) Leak repair qualified: a. Meets the requirements for oil-free equipment ； b. For defects that cannot be addressed immediately, take measures to direct the oil back to the oil sump. 4. Methods for addressing oil leaks. There are many ways to fix leaks in equipment; generally, treatment should be carried out in accordance with the principles of sealing, blocking, diverting, and pressure equalization, tailored to the specific situation. The eight-principle approach of modifying, replacing, sealing, diverting, blocking, connecting, repairing, and managing pipes serves as a summary of the mass-based efforts to address leaks. (1) Modification: For unreasonable sealing structures, replace them with materials that are less prone to leakage or improve the pressure difference in the system to achieve a leak-free condition. (2) Replace: Replace damaged or poorly performing seals and fittings. (3) Plugging: To seal oil leakage points by using plugging or sealing methods due to design or manufacturing defects. (4) Sealing: Sealing is not a permanent blockage; it merely improves the sealing performance at the joint. (5) Introduction: Use a diversion method to ensure smooth return of oil, allowing excess oil to be promptly drained back to the oil sump. (6) Connection: For lubrication areas where drainage is not possible structurally, oil pipes, oil baffle plates, oil collection trays, etc. are added to channel the oil back to the oil tank. (7) Repair: Fix the parts causing leaks, weld or seal pores and cracks, and repair the sealing areas. (8) Management: Strengthen management and inspections to detect issues promptly and address them at any time. 5. Sealing technology: Sealing is an important measure to prevent the leakage of lubricating materials and to stop harmful substances from entering the friction areas and contaminating the lubricating materials. 6. Classification of seals: Based on the relative motion between the joined surfaces, seals can be classified into static seals and dynamic seals. (1) Static seal: The sealing of a stationary mating surface is called a static seal. A static seal achieves sealing at the interface by relying on the plastic deformation of the sealing material or its filling into uneven areas. Based on the type of sealing material, they can be classified into non-metallic seals, metallic seals, composite seals, and sealant seals. Non-metallic seals: Types include gaskets, sealing strips, etc. Materials include fiberboard, asbestos rubber, oil-resistant rubber, leather, plastic, etc. Suitable for sealing joints and plugs that are not removed frequently. Metal seals: Types include flat gaskets, wave-shaped gaskets, serrated gaskets, lens-type gaskets, etc. The materials include aluminum, lead, red copper, low-strength soft steel, etc. Suitable for sealing joints and flange connections of high-pressure oil pipes and steam pipes. Composite seal: In the form of a flat gasket. The materials include metal-encased asbestos boards, wire-reinforced asbestos boards, metal-wrapped asbestos boards, and metal-silicone gaskets. It is mainly used for sealing high-temperature, high-pressure gases and cylinder heads. Sealant sealing (liquid gasket sealing): Sealant is a viscous, flowable paste. It provides excellent leak-proof sealing performance when applied to sealed areas. Based on their form in operational conditions, they are classified as dry, non-dry, and semi-dry. Based on their composition, they include phenolic resin type, epoxy resin type, neoprene type, and nitrile rubber type, among others. (2) Dynamic sealing: The sealing between two relatively moving parts is called dynamic sealing. Most involve the sealing of the rotational and reciprocating movements of the shaft with the housing or end cover. They are divided into contact and non-contact types. ① Contact seal is used for sealing liquid and gas media as well as preventing dust ingress. Contact seals are classified by seal type into packing seals, cup seal seals, mechanical seals, etc. a. Packing seals: The materials used include felt strips, rubber-asbestos packing, polytetrafluoroethylene packing, and rubber seals with woven fabric inserts; they can be used for sealing the rotary or reciprocating motion of liquids and gases ； b. Bowl seal sealing (lip seal): These are mainly bowl-shaped seals made of materials such as rubber, rubber composite fabrics, polyurethane, and plastics. There are various frameless or framed oil seals, as well as sealing rings in Y-shaped, U-shaped, J-shaped, L-shaped, and other forms ； c. Mechanical seals: Mechanical dynamic seal structures come in various types; due to their excellent sealing performance, they are suitable for sealing pumps that transport liquids and gases under conditions of high speed, high pressure, corrosive environments, toxic conditions, or in vacuum settings. ② Contactless sealing: Contactless sealing is not restricted by speed or temperature, involves no wear, and is suitable for sealing gases and liquids as well as preventing dust ingress. Based on their structure, they can be classified into labyrinth seals, dynamic seals, magnetohydrodynamic seals, pneumatic seals, and spiral seals, among others. a. Labyrinth seal: The labyrinth ring creates resistance to the flow of gas or liquid, making leakage difficult. Also used for dust sealing of rotating shafts ； b. Dynamic sealing: It is used for sealing the rotating shafts of pumps. A specially designed auxiliary impeller or vane generates pressure in the opposite direction to that of the main impeller, preventing the liquid from leaking out through the gaps in the rotating shaft. It features reliable sealing and a long service life, meeting the requirements for wear resistance and resistance to corrosion. Primarily used for sealing in chemical pumps ； c. Magnetohydraulic sealing: A magnetic fluid is contained within the sealing ring, and it is primarily used for sealing low-pressure gases as well as preventing dust from entering ； d. Air pressure sealing: Utilizes the pressure of compressed air to prevent liquid from leaking through the gaps in the rotating shaft. Compressed air is required, and the gas pressure should be 0.03~0.05 MPa higher than that of the sealing medium ； e. Spiral seal: Utilizes the principle of a screw pump to push the liquid leaking from the gap back into the housing. The spiral direction should match the rotation direction of the shaft. It performs poorly at low speeds. Suitable for sealing high-speed, high-temperature liquid pumps. 7. Performance and applications of common elastic seals. Elastic seals are most widely used for sealing in lubrication systems.