Extending the Lifespan of Medium Frequency Bending Machines

Extending the Lifespan of Medium Frequency Bending Machines: A Comprehensive Systematic Maintenance Guide from Principles to Operations

In the pipeline processing industry, medium frequency bending machines, with their advantages of uniform heating, high bending accuracy, and outstanding production efficiency, are widely used in pipeline prefabrication work in engineering fields such as power, petrochemicals, shipbuilding, and nuclear power construction. However, how long can a medium frequency bending machine last? The answer is not a single figure on the equipment's nameplate, but is determined by design quality, operating conditions, operational norms, and daily maintenance. For users, the long-term stable operation of the equipment means lower overall costs and more reliable production guarantees. This article will start from the working principle and systematically analyze practical methods to extend the lifespan of medium frequency bending machines, covering daily maintenance, key system maintenance, standard operation, and common fault prevention, providing a practical maintenance guide for equipment managers. 1. Working Principle: Understanding the Equipment is the Foundation of Correct Maintenance Medium frequency bending machines mainly operate based on the principle of electromagnetic induction. The working process is as follows: a heating coil is placed on the part of the pipe to be bent, the pipe head is clamped by a mechanical arm, and a medium frequency current is passed through the heating coil to heat the pipe. The medium frequency induction heating causes the metal object to have eddy currents that circulate on the surface layer at a higher frequency, and the heating depth of the metal object can be controlled by adjusting the working current frequency. When the temperature of the pipe rises to the plastic state (usually in the 970-1020℃ austenite region), the pipe is pushed forward at the rear end using a mechanical thrust, and the bent pipe is formed. The bent pipe is quickly cooled with a coolant while heating, advancing, bending, and cooling continuously, and the pipe is bent out piece by piece. From the perspective of system composition, a complete medium frequency bending machine mainly consists of the medium frequency induction heating system, cooling water system, hydraulic propulsion system, and mechanical transmission system of the reducer. Understanding this working principle and the functions of each system can better grasp the necessity of each maintenance measure. 2. Daily Maintenance: The Foundation of Foundations The maintenance of medium frequency bending machines should start from daily operations. Establishing a hierarchical maintenance system - daily inspection, weekly inspection, and monthly inspection - is the most economical and effective means to prevent faults from occurring, rather than passive repair. 1. External Inspection and Foundation Check Before starting the machine each day, operators should conduct a comprehensive inspection of the equipment: observe whether the surface of the equipment is clean, confirm that there is no dust or oil stains; check whether the oil circuit and oil pipes of the lubrication system are unobstructed and whether the oil is sufficient; check all fasteners to ensure they are in a tightened state; check for wear or breakage of the cables; check whether the switches, contactors, relays, etc. of the electrical system are firmly connected. In addition, it is necessary to check whether the cooling water circulation pump, oil pump, etc. are normal and intact, and confirm that all parts of the equipment are in a standby state before starting. These seemingly trivial inspection tasks are often the key windows for discovering early hazards. 2. Maintenance Key Points of the Hydraulic System The hydraulic system is the core channel for transmitting power in medium frequency bending machines, and its health condition directly determines the performance of the equipment. The first is the management of hydraulic oil level, which should be checked daily before starting the machine to ensure that the hydraulic oil level is at 1/2 to 2/3 of the oil gauge. Insufficient oil level will cause the system to suck air, and excessive oil level may cause system failure and damage to the seals. The control of hydraulic oil temperature is also not to be ignored. During operation, the hydraulic oil temperature should be controlled within the range of 30-50℃. When it exceeds 60℃, the cooling system should be activated to cool down. Long-term operation of the hydraulic system in high temperatures will significantly accelerate the aging of seals and the wear of pump valves. The working environment temperature should also be maintained between -10℃ and 50℃ to ensure the stable operation of the system. The standard for replacing hydraulic oil has a clear industry consensus: when the equipment has been running for more than 2,000 hours, or when the oil contamination reaches NAS 10 level, it is necessary to replace the oil. The color of the oil changes from light yellow to brown-black or shows emulsification and sedimentation, which are also signals that require replacement. In addition, the oil tank should be cleaned and the hydraulic oil filtered once within 1-2 months after the equipment starts to be used. Then, the inlet filters of each pump should be thoroughly cleaned according to the cycle. 3. Lubrication Management: The Most Economical Means to Extend the Service Life of Mechanical Components Reasonable lubrication not only reduces wear between friction pairs but also effectively dissipates heat and prevents rust and corrosion. The types of lubricating oil required for each moving part of the medium-frequency bending machine are different: the hydraulic system uses anti-wear hydraulic oil, the gearbox uses industrial gear oil, the sliding guide rails and screws use guide oil, and each bearing position should use lithium-based lubricating grease. Do not use the same type of lubricating oil throughout. For key parts such as screws and guide rails, NLGI 2-grade lithium-based lubricating grease should be added once a week to ensure adequate lubrication. Regularly perform lubrication maintenance on each lubrication part of the medium-frequency bending machine is a necessary measure to reduce friction and extend the service life of mechanical components. 4. Cooling Water System Maintenance The cooling system is crucial for the normal operation of the medium-frequency bending machine. The quality of the circulating water directly affects the machine's efficiency and the lifespan of various consumables, accessories, and the main unit. The water tank should be cleaned and the water replaced once a week. It is recommended to inject fresh pure water or distilled water. In summer, when the water temperature is high, effective measures should be taken to keep the water temperature constant. In addition, cooling water pipes should be cleaned regularly to prevent internal scaling that affects the cooling effect; regular checks on the operation of the cooling water circulation pump are necessary to ensure its normal operation. During use, it is important to note that when the transformer is running (including no-load), the cooling water supply must not be interrupted. The water path should be kept flowing to prevent water from splashing onto the transformer and causing damage. III. Special Maintenance Strategies for Core Systems Each core system of the medium-frequency bending machine has different working characteristics and wear patterns, requiring targeted maintenance measures. 1. Medium-frequency Heating System (Induction Coil and Medium-frequency Power Supply) The induction coil is the core component of the heating system of the medium-frequency bending machine. During long-term use, the coil may age due to thermal fatigue and oxidation. Its lifespan is usually 3-6 years. Regularly check if there are any obvious damages or deformations on the appearance of the induction coil, and use a multimeter to measure the resistance of the induction coil to ensure it is within the normal range. The power components in the medium-frequency power supply cabinet, such as thyristors and capacitors, have a longer lifespan of 8-10 years under good heat dissipation and stable voltage conditions. Therefore, ensuring good heat dissipation of the power cabinet and cleaning the internal dust regularly has a significant effect on extending the lifespan. During the bending process, it is also necessary to closely monitor the state of the heating belt. During operation, monitor the gap around the induction coil and the cooling condition of the spray holes. If necessary, make adjustments and open holes to ensure uniform heating of the bending belt. If the induction coil shows abnormalities, the reasons may include coil damage, poor circuit connection, or unstable power supply voltage, and it is necessary to promptly investigate. 2. Special Maintenance of the Cooling System The cooling system is an important link to ensure the normal operation of the equipment. If the cooling is poor or the cooling water circulation is not smooth, the heat dissipation effect of the equipment will decrease, and the temperature of each component will rise, resulting in a shorter lifespan. The common causes of cooling system problems include poor cooling water quality, damaged cooling water circulation pump, and blocked cooling water channels. Therefore, regular inspection of the cooling system's water quality is necessary to keep it clean; regular checks on the operation of the cooling water circulation pump to ensure the normal operation of the water pump and the water cooling system can effectively reduce the equipment temperature; and regular cleaning of the cooling water channels to prevent blockages. 3. Deep Maintenance of the Hydraulic System The maintenance of the hydraulic system is the most important part of the maintenance work for the medium-frequency bending machine. Each connection of the hydraulic pump station is equipped with an oil-resistant rubber sealing ring. If the sealing ring is damaged and oil leaks, it should be replaced in time. The selection of hydraulic oil is related to the performance of the system. The commonly used hydraulic oil model is L-HM46 (viscosity at 40℃ is 46 mm²/s). In low-temperature environments (-10℃ and below), L-HV46 low-temperature hydraulic oil should be selected. For high-pressure systems, anti-wear hydraulic oil should be used. If the forward and backward movements of the mechanism fail, first check if the electromagnetic valve is operating normally. If the electromagnetic valve is normal, then check if there are impurities blocking the sequence valve, overflow valve or one-way relief valve. This phenomenon is more common when the equipment is first used. If there is a blockage, it can be cleaned with gasoline or diesel and reinstalled. 4. Maintenance of mechanical transmission system and reducer The mechanical transmission system is an important component for achieving bending actions. Daily inspection and regular lubrication are indispensable. Regularly check the operation of transmission components such as gears, chains, and bearings to replace worn-out parts in time. At the same time, regularly inspect the structure of the bending machine frame to ensure it is stable and reliable, with no obvious deformation or cracks. The failure of the reducer should also not be ignored. Common problems with reducers include oil leakage, abnormal noise, and excessive vibration. The causes of oil leakage are mostly related to temperature changes causing sealing failure, abnormal oil level, or structural issues. If the reducer leaks oil, it should be checked whether the sealing ring is aging, the oil level is appropriate, and the vent cap is blocked. Excessive oil addition will cause a large amount of lubricating oil to accumulate at the shaft seal, increasing the risk of oil leakage. Improving the ventilation cap and inspection cover plate to balance the pressure inside and outside the machine can effectively reduce or avoid oil leakage. Once there is abnormal noise or vibration in the reducer, the machine should be stopped for inspection to avoid small problems evolving into major faults. Four. Standard Operating Procedures: Human Factors Are the Most Flexible Variable An excellent medium-frequency bending machine, if operated improperly, may significantly reduce its lifespan; conversely, correct operating habits can effectively extend the equipment's service life. . Startup Preparation and Preheating Before starting, check if all lubrication points are lacking oil, if the safety protection device is reliable, and if the moving mechanism is loose. Confirm everything is correct before operating. Start the cooling water system and adjust the water pressure to the required pressure for the bending pipe. After starting the oil pump, check if the system pressure remains within the specified range. Excessive pressure will damage the hydraulic components and waste electrical energy, while too low pressure will affect normal operation. After the cold machine starts, the hydraulic oil temperature is low and the viscosity is high. Directly putting it into high-load operation will cause the hydraulic pump to suck air and abnormal pipeline pressure. If this continues for a long time, it will seriously damage the hydraulic system. The correct approach is: start the machine and run it at no-load for a period of time to allow the oil temperature to gradually rise to the appropriate working range (35-55℃), then start normal production. 2. Operating Specifications during Bending Process During the bending process, the push speed should be closely coordinated with the temperature. After the medium-frequency power supply is turned on, wait until the steel pipe is heated to the minimum temperature required for bending, then slowly adjust the oil volume to start pushing the pipe, closely monitoring the matching of the pushing speed and the heating temperature to ensure that the heating temperature does not exceed the allowable range. For thick-walled pipes with a bending diameter greater than 300mm or a wall thickness greater than 30mm, if the one-time heat penetration is unsuccessful (the outer wall temperature reaches above 850℃ while the inner wall is not red), low power should be used to extend the heat penetration time, or intermittent heating methods should be used to transfer heat. It is strictly prohibited to forcibly bend the pipe when the temperature difference between the inner and outer walls is too large. 3. Handling of Abnormalities and Emergency Shutdown Operators should always pay attention to changes in the equipment's operating sound, vibration, and temperature during production. If they hear abnormal sounds (such as metal impact sounds, sharp friction sounds), feel a significant increase in vibration, or smell an abnormal odor, they must immediately stop the machine for inspection, and only resume production after the fault is eliminated. Operating with a faulty machine is most likely to cause "minor problems evolving into major ones". In case of water or power outages, stop the machine immediately and retract the cylinder in time. If the pipe is still hot when bending, the rotating arm can be slightly retracted to relieve the force on the pipe, and then the bending can be carried out after restarting to avoid wave-like deformation or cold drawing at the connection point. 4. Shutdown Procedure The shutdown procedure for bending should follow the specified sequence: first, stop the heating power supply and the oil quantity control valve, then stop the cooling water according to the cooling condition of the heating belt, and immediately release the front chuck (to prevent rebounding after cooling and making it difficult to open), then retract the cylinder, and finally stop all accessory systems. Standard shutdown operations can not only protect the equipment but also lay a good foundation for the next startup. V. Common Faults and Their Prevention Understanding the manifestations and causes of common faults can help to actively prevent problems before they occur or quickly eliminate them after they occur. 1. Cracks or fractures during bending The possible causes of such problems include: defects in the material itself, excessive heating temperature or too low temperature, too small bending radius, or too fast bending speed. Preventive measures include: checking the material quality to ensure there are no defects; adjusting the heating temperature and time to ensure uniform heating of the pipe; appropriately increasing the bending radius, reducing the bending speed; using lubricants during the bending process to reduce friction between the pipe and the mold. 2. Heating abnormalities (sensor abnormalities) Abnormalities in heating will directly affect the quality and efficiency of bending. The possible reasons may include sensor damage, poor line connection, unstable power supply voltage, etc. The solutions include: checking if the sensor is damaged (if necessary, replace it immediately); checking the connection of the line to ensure there is no looseness; ensuring stable power supply voltage to prevent the influence of voltage fluctuations on the sensor. 3. Mechanical transmission system failure Mechanical transmission system failures may result from gear wear, chain breakage, bearing damage, etc. The key to prevention lies in regularly checking the operation of each component, replacing worn-out parts in a timely manner, and strengthening the lubrication and maintenance of the equipment. 4. Cooling system problems If there is poor cooling or poor circulation of cooling water, regular checks should be made on the operation of the cooling water circulation pump and the water quality, maintaining clean water quality; at the same time, regularly clean the cooling water channels to prevent blockage and ensure the system's heat dissipation effect. VI. Comprehensive Management Suggestions for Longevity Extension To ensure that a medium-frequency bending machine operates stably for more than ten years, it is necessary to manage from multiple aspects: 1. Establish maintenance files: Fill in the equipment maintenance and repair records on time, including daily inspections, weekly maintenance, monthly inspections, and deep overhaul every year. Complete files are not only the basis for maintenance but also the foundation for analyzing the deterioration trend of the equipment. 2. Reasonably formulate maintenance plans: Divide maintenance work into three levels: daily inspection, weekly inspection, and monthly inspection. Daily maintenance checks oil levels, lubrication, and abnormal vibrations; weekly maintenance adds grease, checks mold torque; monthly inspection checks hydraulic system pressure, replaces filters, and backs up control programs. 3. Regularly replace wear parts: Replace wear parts of the medium-frequency bending machine, such as bearings and sealing rings, according to the equipment usage situation to ensure long-term stable operation. 4. Keep the equipment clean: Before leaving work, clean the machine tool, keep the surrounding environment of the bending machine clean, and regularly lubricate and clean the tracks, screw rods, etc. 5. Regular deep overhaul: The regular deep overhaul of the medium-frequency expansion machine can be divided into two levels: semi-annual inspection and annual overhaul. The semi-annual inspection checks the wear condition of the molds (generally allowing a wear amount of 0.1mm or less); the annual overhaul checks the operation status of each system in a more comprehensive manner. Conclusion The medium-frequency bending machine, as a key equipment for pipeline processing, its lifespan extension requires not only continuous optimization by manufacturers during the design and manufacturing process, but also the dedicated efforts of users in daily maintenance. From cleaning the appearance to replacing the hydraulic oil, from inspecting the cable lines to repairing the induction coils, every seemingly ordinary maintenance task is accumulating "credit points" for the long-term stable operation of the equipment. For enterprises, the total life cycle cost of the equipment is much higher than the initial purchase cost. Instead of passively repairing after equipment failure, it is better to actively maintain from daily details; instead of frequently replacing components, it is better to establish a systematic maintenance management system. A well-maintained medium-frequency bending machine can operate stably for more than ten years, providing continuous and reliable support for the production line. This is precisely the wisdom of equipment management.