Causes and Preventive Measures of Quenching Soft Spots of Slewing Bearings

In the production process of the slewing bearing, the hardness of the steel ring is locally lower after the quenching process, which usually occurs after the quenching. This situation is called the quenching soft point, and when the pieces appear, it is called the quenching soft belt. The location where the soft spot occurs is that the bearing has low hardness, which will affect the quality of subsequent grinding. Fatigue damage is also prone to occur during use, which affects the service life of the bearing. So what is the reason for the quenched soft spot of the slewing ring?

Reasons for the soft spot of slewing bearing quenching

1. Decarburization: When the metal is heated in the furnace or the atmosphere in the furnace is not good, it is easy to cause decarburization. The process of decarburization is that the carbon element in the bearing steel reacts with clear or oxygen at high temperature to generate methane or carbon monoxide. This situation will reduce the surface carbon content and the hardness to meet the requirements.

2. Insufficient temperature: Insufficient heating temperature and insufficient heat preservation make the bearing material matrix not fully austenitized. After quenching, it cannot completely transform into martensite, resulting in local soft spots. In addition, the local cooling rate is too low, the bearing surface has bubbles or contaminants, or the critical cooling rate is not reached in the close contact of the workpiece, and it cannot all become martensitic.

3. Uneven steel structure: If the original structure of the workpiece material used in the production of the bearing is not uniform, such as carbide segregation, carbide aggregation, etc., it will affect the quenching effect of the bearing.

4. Inductor problem: The structure of the inductor and the positioning fixture during quenching are not good, which affects the heating effect, or the center line of the spray cooling hole on the inductor and the quenched surface are perpendicular or angled improperly, resulting in uneven heating, heating, and cooling. The situation arises. In addition, the unequal spacing between the bearing and the inductor can also cause uneven heating.

5. Poor hardenability: The material of the slewing bearing is made of steel with poor hardenability, such as carbon steel. However, if the cross section of the workpiece is large or the thickness difference is large, soft spots may appear at the large cross section.

6. Poor quenching medium: the cooling rate of the quenching medium is low or too old will cause soft spots in the bearing.

After understanding the reasons for the soft spots or soft bands of the slewing bearing, the method to improve the existing soft spots can be through annealing, normalizing, and high temperature tempering, followed by re-quenching according to the normal process, or re-quenching after recarburizing. Or, after quenching, the hardness can be improved by cold treatment, and then tempering treatment will try to solve it. So how do we avoid the recurrence of quenched soft spots in the subsequent bearing production and processing process?

Slewing Bearings

Measures to prevent the occurrence of soft belts on slewing bearings

1. Reasonable material selection: pre-homogenize the defective steel before quenching to remove the problems of carbide segregation and aggregation.

2. Control the heating temperature and time: For insufficient austenitization due to insufficient heating temperature and time, we need to select the appropriate heating temperature, heating time, and holding time for the steam during processing.

3. Reasonable selection of quenching medium: strengthen the relative movement between the workpiece and the medium, or stir the medium to keep the quenching medium clean. Quenching of carbon steel in salt water can effectively prevent the generation of soft spots.

4. Strictly follow the process: perform the quenching operation correctly, correctly control the pre-cooling time, the residence time in water or brine during quenching, the residence time in water or brine during dual-medium quenching, and the residence time of graded quenching.

The above is the reason for the soft spot of slewing bearing quenched by Lunda editor and the measures to prevent the soft band. I hope it can be helpful to everyone. The soft spots of the bearing have an impact on the later grinding process and performance of the bearing. I hope everyone will pay attention to it.

Why should the slewing bearing be pickled? Pickling process

In our production process, the process of cleaning and degreasing the metal parts and soaking them in an acid solution is usually called pickling. Bearings also need to be pickled, so why should slewing bearings be pickled?

There are two main purposes, one is to remove oxide scale or burrs on the metal surface by pickling, and the other is to pickling to check metal surface defects to see if there is burn corrosion. The editor of Lunda will introduce to you the specific operation process of slewing bearing pickling.

The purpose of pickling of slewing bearings

slewing bearings

1. Surface purification: Use pickling or chemical cleaning to clean the bearing surface, such as pickling before electroplating, pickling before phosphating, pickling to remove oxide skin burrs, etc. Use pickling liquid to choose cold pickling or hot pickling according to the condition of the metal surface. It is widely used to remove oxide scale on the surface of the cage.

2. Pickling inspection: Use pickling to check the bearing surface defects, which is called pickling inspection or burn corrosion. It is a kind of detection method, commonly used in cold pickling with nitric acid. If the metal surface has cracks, decarburization, peeling, burns and other defects, it can be manifested by cold pickling. In foreign countries, this pickling inspection technology is often classified into the NDT (no inspection) method. Most domestic factories use this inspection method to detect the presence of surface defects.

According to different application purposes, processing requirements and different raw materials, select the correct pickling technology and use the appropriate pickling process (including the selection of acid solution, corrosion inhibitor, process steps, pickling time, etc.), and a special The pickling staff conduct operations and inspections to ensure the pickling effect and the quality of the bearing products. Let’s take a look at the operation process of pickling with Ronda editor.

The process flow of slewing bearing pickling

slewing bearings

1. Preparation before pickling: the bearing parts need to be cleaned before pickling, and the surface should not be dirty with oil, magnetic powder, dust, etc.; if the surface is severely rusted, it needs to be derusted and then pickled.

2. The pickling process:

(1) Put the bearing into a metal cleaner solution for soaking. The concentration of the solution is required to be 4%~5%, and the temperature should be controlled at 75~90℃. If it is pickling, use normal temperature water to dilute the solution. The soaking time is not less than 1 minute.

(2) During the process, the bearing should be shaken or moved to make it fully contact with the solution, and the solution should be kept clean, and the pickling time should be controlled within 5 minutes.

(3) Rinse the soaked bearing in flowing cold water and cool it to room temperature.

3. Inspection after pickling: Check the appearance of the bearing. Its surface should be consistent silver gray or light gray. Generally, the burned position will appear black or bright white, the soft spot position will be dark gray or black, and the decarburized position will be off-white. During the inspection process, the bearing surface is not allowed to be wiped. If in doubt, use absorbent cotton dipped in ethanol or anti-rust solution to wipe.

Slewing Bearings

After the inspection is completed, the bearing should be sent to the anti-rust process in time for treatment to avoid re-oxidation and corrosion of the surface.

3. Precautions for pickling of slewing bearings

1. During the pickling process, the operation should be carried out strictly in accordance with the process sequence, and the process sequence should not be randomly selected.

2. Keep Lingshui flowing and clean during the pickling process and avoid turbidity.

3. The whole process should be carried out under the conditions of good ventilation and safety protection.

4. When replacing the pickling solution, the cleaning tank needs to be cleaned, rinsed with clean water 2-4 times and then the solution is prepared.

5. When preparing the diluted solution, pour the concentrated acid into water or alcohol and keep stirring. If there is solid, stir the solid first and then add the concentrated acid. It is forbidden to pour water into the concentrated acid, which is prone to splashing or danger. accident.

The above is a specific introduction on why the slewing bearing should be pickled and the pickling process. I hope to help everyone better understand the purpose and meaning of pickling. At the same time pickling can help the bearing achieve better performance

Why should the slewing bearing be annealed?

Why should slewing bearings be annealed? In fact, annealing of slewing ring bearings is a process of bearing heat treatment. Generally, the bearing metal is heated to a certain temperature and kept for a period of time, and then the metal is cooled at a suitable speed. This method improves the toughness of the bearing steel. , Reducing bearing hardness and residual stress can reduce the probability of deformation and cracks, and enhance the stability of bearing materials.

Why should the slewing bearing be annealed?

There may be three reasons for the purpose of annealing the slewing bearing:

1. The annealing process can reduce the hardness of the bearing steel, improve the plasticity, and facilitate the later cutting and deformation processing.

2. Annealing can refine the grains of bearing materials, eliminate structural defects caused during bearing casting, forging, and welding, and uniform the structural structure and steel composition of the steel, which can improve the performance of the steel and prepare for the later heat treatment.

3. The annealing process can eliminate the internal stress in the steel and prevent or reduce the possibility of deformation and cracking of the bearing. In one case, the annealing process is not only for metal materials but also for annealing of non-metal materials. After understanding why slewing bearings should be annealed, the following editor will introduce the types of annealing processes for slewing bearings. In fact, there are many types of annealing processes, and different steel structures are suitable for different processes.

Annealing process type of slewing bearing

Slewing Bearings

1. Recrystallization annealing

Recrystallization annealing is also called full annealing, which is an annealing process in which iron-carbon alloys are austenitized and then slowly cooled or close to equilibrium. The heating temperature of carbon steel is generally Ac3+ (30~50℃); alloy steel is Ac3+ (500~70℃); the holding time depends on the type of steel, the size of the workpiece, the amount of furnace installed, the selected equipment model, etc. The factors are determined. In order to ensure that the undercooled austenite undergoes the pearlite transformation, the cooling of the recrystallization annealing must be slow, and the furnace is cooled to about 500°C and then air-cooled.

This annealing process is mainly used for hypoeutectoid steels, generally medium-carbon steel and low- and medium-carbon alloy structural steel forgings, castings and hot-rolled sections, and sometimes also used for their welding components; it is not suitable for hypereutectoid steels, Because the recrystallization annealing of hypereutectoid steel needs to be heated to above Acm, during slow cooling, cementite will precipitate along the austenite grain boundary and present a network distribution, which will increase the brittleness of the material and leave hidden dangers for heat treatment.

2. Uniform annealing

Uniform annealing is also called diffusion annealing, in order to reduce the segregation of the chemical composition of metal castings or forging billets and the unevenness of the structure. It is heated to a high temperature, maintained for a long time, and then slowly cooled to homogenize the chemical composition and structure. Purpose of annealing process. The heating temperature of homogenization annealing is generally Ac3+ (150~200℃), that is, 1050~1150℃, and the holding time is generally 10~15h to ensure the full progress of diffusion and the purpose of eliminating or reducing the uneven composition or organization. Because the heating temperature of diffusion annealing is high, the time is long, and the crystal grains are coarse, for this reason, recrystallization annealing or normalizing is performed after diffusion annealing to re-fine the structure.

Slewing Bearings

3. Incomplete annealing

Partial annealing is an annealing process in which the iron-carbon alloy is heated to a temperature between Ac1 and Ac3 to achieve partial austenitization, followed by slow cooling. Partial annealing is mainly suitable for medium and high carbon steel and low alloy steel forgings, etc. Its purpose is to refine the structure and reduce the hardness. The heating temperature is Ac1+ (40-60) ℃, and the temperature is slowly cooled after heat preservation.

4. Stress relief annealing

One of the key reasons why slewing bearings should be annealed is the annealing process in order to eliminate the residual stress caused by plastic deformation processing, welding, etc. and the residual stress in the casting. There are internal stresses in the workpiece after forging, casting, welding and cutting. If it is not eliminated in time, the workpiece will be deformed during processing and use, which will affect the accuracy of the workpiece. It is very important to use stress relief annealing to eliminate internal stress generated during processing.

5. Isothermal annealing

Isothermal annealing is to heat the steel or blank to a certain temperature and keep it for a period of time, and then quickly cool it to a certain temperature in the pearlite temperature range and keep it isothermally, so that the austenite is transformed into a pearlite structure, and then in the air Cooling annealing process. This process is suitable for medium carbon alloy steel and low alloy steel, and its purpose is to refine the structure and reduce the hardness. The heating temperature of hypoeutectoid steel is Ac3+(30~50)℃, and the heating temperature of hypereutectoid steel is Ac3+(20~40)℃. Keep it for a certain period of time, and then perform isothermal transformation with furnace cooling to slightly lower than Ar3 temperature, and then air cooling out of the furnace . The isothermal annealing structure and hardness are more uniform than recrystallization annealing.

6. Spheroidizing annealing

Spheroidizing annealing is an annealing process to spheroidize carbides in steel. Heat it to 20-30°C above Ac1, keep it for a period of time, and then slowly cool it to obtain a structure of spherical or granular carbides uniformly distributed on the ferrite matrix.

Spheroidizing annealing is mainly used for hypereutectoid steel and alloy tool steel (such as cutting tools, measuring tools, molds, bearings and other steel grades). The main purpose is to reduce the hardness, improve the machinability, and prepare for later quenching. There are many spheroidizing annealing process methods, and the two commonly used processes are ordinary spheroidizing annealing and isothermal spheroidizing annealing. Compared with ordinary annealing methods, spheroidizing annealing can not only shorten the cycle, but also make the spheroidized structure uniform, and can strictly control the hardness after annealing.

7. Recrystallization annealing

Recrystallization annealing is also called intermediate annealing. It is a heat treatment process in which the cold-deformed metal is heated to a temperature above the recrystallization temperature and kept for an appropriate time to recrystallize the deformed grains into uniform equiaxed grains to eliminate deformation strengthening and residual stress. .

The above is an introduction to the reasons why slewing bearings should be annealed, which also includes the types of annealing processes and their respective characteristics and process introductions. I hope to help everyone have a clearer understanding of the annealing process.

How to judge the operating status of the slewing drive? Common faults and solutions

Slewing drives are widely used due to their modular installation convenience, operational stability, load-bearing capacity and strong environmental adaptability, etc., to improve industrial production efficiency and accelerate the realization of industrial automation. Then, once a failure occurs during the operation of the equipment, it may affect the normal production plan. For this reason, we should pay attention to the operation of the equipment and make timely judgments.

Judgment method of slewing drive operating state

SE Series Slewing Drive

1. Pay attention to the backhaul gap

During the operation of the equipment, observe the clearance of the rotary reducer during the return stroke, and judge the return clearance of the drive by the instant forward and reverse operation mode during operation. Refer to the theory of the type of rotary reducer corresponding to the instruction manual provided when the drive is purchased. The return gap can be used to judge whether the running state is normal.

2. Listen to the running sound

Normal equipment operating sounds are different from abnormal sounds. How to determine the operating status of the slewing drive can start from identifying the abnormal sounds. For abnormal noises or irregular sounds during operation, it is necessary to judge whether the reducer is in normal operation. If there are abnormal sounds, it should be repaired in time to determine the damage location and repair it.

3. Observe the operating temperature

If the slewing drive has abnormal temperature, there may be problems with overload operation or bearing wear and abnormal voltage, but these are usually not directly reflected from the operating state when the equipment is running, so we can judge by the temperature of the drive during operation. If the temperature is too high, it needs to be overhauled in time.

If all the above conditions are normal after running for more than 30 minutes, it means that the rotary reducer is in good working condition and can be used with confidence. So, the following editor introduces some common faults of rotary reducers for reference only.

Common faults and solutions of slewing drive

S Series Slewing Drive

1. The motor does not rotate: the motor does not rotate. Eliminate power failure and poor switch contact. There may be problems such as abnormal voltage, gear damage, overload operation, coil breakage, etc. You need to check the power supply, wiring, voltage, capacitor or directly contact the manufacturer for repair.

2. Abnormal heating: Abnormal heating of the drive may be caused by overload operation, abnormal voltage, bearing wear, etc. It is necessary to reduce the load and frequency of use, confirm whether the voltage is normal and perform maintenance.

3. Noise: The noise of the rotary reducer may have bearing damage, gear wear, or foreign matter jamming, and it needs to be disassembled and repaired by the manufacturer’s service personnel. Or there is lubricating oil contaminated or lack of lubricating oil, it should be supplemented or replaced in time.

4. Abnormal vibration: abnormal vibration caused by loose screws or wear of gears and bearings requires screw progress or replacement and maintenance of gear bearings.

5. Oil leakage: There are reasons such as loose screws or damage to the sealing ring, and the screws should be replaced or tightened in time.

The above are several judgment methods of Lunda editor on how to judge the running status of the slewing drive, as well as the common faults and solutions of the equipment. I hope it will be helpful to everyone. In the daily use of the reducer, you should pay attention to the running status of the equipment and find the problem in time. Repairs to prevent the deterioration of the problem from affecting production.

How to install the slewing drive? Installation method and process

The installation of the slewing drive device directly determines its fluency during the operation of the machine and the probability of failure during use. Improper installation may cause damage to it and affect its service life. Therefore, the installation is very important for the slewing drive. I don’t know how much you know about how to install the slewing drive.

Slewing drive installation tool

1. Auxiliary tools for hardware removal and installation such as wrenches, pliers, bolt tighteners, etc.;

2 Cleaners such as diesel, banana water, gasoline, etc.;

3. Scraper (used to clean up impurities on the supporting surface);

4. Feeler gauge, used for measurement in the later installation process;

HSE-2

Preparation before installation

1. Before installation, confirm whether the motor and the slewing drive are intact, and check whether the dimensions of the parts connected to the slewing drive match.

2. Screw on the screw on the dust-proof hole on the outside of the rotary drive flange, adjust the PCS system clamping ring to align the side hole with the dust-proof hole, and insert the inner hexagon to tighten. Then remove the motor shaft key.

3. Before installation, wipe the motor input shaft, positioning boss and the anti-rust oil at the connection part of the reducer with gasoline or zinc-sodium water.

4. Clean the impurities on the support surface (for example, iron filings, burrs, paint, welding slag, etc.).

5. Clean the anti-rust oil on the mounting surface of the rotary reducer.

6. Remove the transportation bolts.

Installation method

1. Fix the rotary reducer on the bracket with bolts, and install flat washers and spring washers on the bolt heads. The rotary reducer should be installed without load.

2. In order to avoid internal stress and installation problems caused by tightening the bolts, please add thread fastening glue to the threads; pre-tightened bolts and washers should be tightened crosswise; starting from the inner or outer ring, all bolts will be diagonal Tighten to 30% of the tightening torque, then tighten the diagonal to the tightening torque of the angle of 30%, and then tighten the diagonal to the mounting bolt, and do not leak. If the bolts cannot be fixed with bolts under structural constraints, the bolt holes must be sealed.

3. If filled with silica gel, it will leak water and dust into the rotary reducer. The installation bolts should consider the thread engagement length, which should not be too long, otherwise it will affect the rotation. Support rotation or cause interference; after tightening the bolt, mark the bolt head and its joint to facilitate future inspection of whether the bolt is loose.

SE Series Slewing Drive

The specific installation process

1. Clean the mounting bracket, remove welding slag, zinc plating residue, etc.;

2. Fix the bracket and the rotary reducer with bolts, and the bolt heads should be equipped with flat washers and spring washers;

3. The rotary reducer should be installed under no load.

4. Add thread fastening glue to the thread;

5. The pre-tightened bolts and washers should be tightened crosswise; the bolt tightening sequence is shown in the figure below; starting from the inner ring or outer ring, all bolts are tightened diagonally to 30% tightening torque, and then repeated diagonally to 50 % Tightening torque, tighten diagonally to 100% tightening torque.

6. The installation bolts are all on top, and no missing installation is allowed. If the bolts cannot be installed due to structural restrictions, the bolt holes must be sealed, such as filled with silica gel, otherwise water and dust will leak into the rotary reducer;

7. The thread engagement length should be considered for the installation bolts, and should not be too long, otherwise it will affect the rotation of the slewing ring or cause interference;

8. After the bolts are tightened, please mark the bolt heads and the joints, which is convenient for checking whether the bolts are loose in the future;

9. Repainting: During the installation of the rotary reducer, it will inevitably cause surface paint bumps and damage. Therefore, after the system is assembled, the rotary reducer needs to be repainted to improve the anti-rust and anti-corrosion capabilities.

After reading the installation method of the slewing drive and the specific installation process, everyone should have a certain understanding of how to install the slewing drive, so let’s take a look at some of the work after the slewing drive is installed.

Maintenance, inspection and lubrication after installation

1. Maintenance and inspection

After the initial assembly is used for about 100 hours, it is necessary to re-tighten the bolts to the specified tightening torque; this inspection needs to be carried out once a year. Under special operating conditions, the number of inspections is relatively reduced. After the bolts are loosened, please replace all bolts, nuts and washers immediately.

2. Lubrication

Lubrication of rotary reducer: The important parts of the product have been lubricated before leaving the factory. We will decide whether to add lubricating ester according to the actual situation during installation. The slewing ring raceway has been filled with grease before leaving the factory; the worm and the slewing ring need to be refilled with grease before use; the tapered roller bearing has been filled with grease before leaving the factory.

HSE Slewing Drive Gearbox

Installation precautions

1. Installation plane

The surface on which the rotary drive is installed should be kept smooth and clean, and the excess materials on it, such as paint residue, welding beads, burrs, etc., should be cleaned. At the same time, the installation surface should be dry and free of lubricant. Specifically, it is necessary to keep the mounting surface roughness of the mounting support not greater than Ra=12.5, 6.3μm. In order to avoid the unevenness of the mounting surface or the deformation of the support causing local overload of the rotary drive, the circumferential flatness error is within any range of 180 degrees. There can only be one wave ups and downs inside, and the changes are gentle.

2. The stiffness of the support

Standard slewing drive and zero-clearance slewing drive have different requirements for the rigidity of the support. Therefore, during installation, a support with corresponding rigidity should be selected according to the specific rotary drive.

3. Positioning

Both the inner and outer ring raceways of the slewing drive have a soft belt, which should be placed on both sides of the main load plane. That is 90 degrees staggered from the main load zone. There is a blockage or “S” mark on the soft belt. In addition, check the fit between the rotary drive and the mounting surface, usually with a feeler gauge. If the fit is not good, fill it with appropriate materials. It is forbidden to weld on the support after the rotary drive is installed.

4. Fastening bolts

Use the specified bolts, and do not use full-threaded bolts, do not use old bolts, nuts and washers, and prohibit the use of open washers such as elastic washers.

After reading this article, I believe that everyone has a certain understanding of how to install the rotary drive. During the installation process, the installation process and precautions must be strictly followed. At the same time, do not forget to check after the installation is completed.

What is the installation process of spur gear drive?

Slewing drive is divided into spur gear slewing drive and worm gear slewing drive. Spur gear slewing drive is also called spur gear drive, gear slewing drive, and gear slewing reducer. Its main applications include solar and wind power generation equipment, robots, radar, low-speed heavy-duty lifting, lifting equipment, precision CNC turntables and other products.

Application principle of spur gear drive

Spur gear drive is a full-circle reduction transmission mechanism that inherits the driving power source. Its working principle is to use all levels of gear transmission to achieve the purpose of speed reduction. The spur gear slewing drive uses a slewing ring as a drive follower and a mechanism attachment. By attaching a driving part and a driving source to one of the inner and outer rings of the slewing ring And the cover, and the other ring is used as the driving follower and the connecting base of the driven working part. In this way, the slewing bearing itself is a full-circle slewing connector, and the driving power source and main transmission parts are configured. Rotary drive is such a general-purpose reduction transmission mechanism that integrates the functions of rotation, speed reduction and driving.

Installation method of spur gear drive

1. Open the package of the slewing drive, check the certificate and label, and confirm that the type of slewing drive used is correct.

2. Make sure to install under no-load conditions, and level the installation position after keeping the surface of the equipment clean.

3. After leveling, install the rotary drive on the equipment support using a wrench, and level the equipment again. The circumferential flatness error can only have one wave ups and downs within any range of 180 degrees, and the change is gentle.

4. Position the equipment and place the soft belts on the inner and outer ring raceways of the slewing drive on both sides of the main load plane. That is 90 degrees staggered from the main load zone. There is a blockage or “S” mark on the soft belt.

5. Tighten up after positioning, use a feeler gauge to measure the fit between the rotary drive and the mounting surface. If the fit is not good, fill it with appropriate materials.

6. Adjust the gear backlash. Use a feeler gauge to measure and adjust the gear radial runout point. If the backlash is not within the specified value, move the pinion to change the center distance, and mark the gear radial runout point in the tooth groove with green paint. .

7. After installation, lubricate the supporting slewing drive, including raceways and gears. In order to ensure sufficient lubrication, the grease specified in the drawing or product instruction manual should be refilled before the first use.

Installation precautions

1. Before installation, confirm whether the motor and gear slewing drive are intact, and check whether the dimensions of the parts connected to the slewing drive match.

2. Screw on the screw on the dust-proof hole on the outside of the rotary drive flange, adjust the PCS system clamping ring to align the side hole with the dust-proof hole, and insert the inner hexagon to tighten. Then remove the motor shaft key.

3. Before installation, wipe the motor input shaft, positioning boss and the anti-rust oil at the connecting part of the speed reducer with gasoline or zinc-sodium water.

4. After the rotary drive is installed, it can be turned by hand, and the application is flexible without jamming. Before starting the machine, fix the connecting screws. The no-load test run should be no less than 2 hours, and the operation should be stable, without impact, vibration, noise and oil leakage. If found, it should be eliminated in time. When using, check whether the fasteners are loose. Ensure normal operation.

5. Naturally connect the motor and the reducer. When connecting, it must be ensured that the output shaft of the reducer and the input shaft of the motor are concentric, and the outer flanges of the two are parallel, so as to extend the service life and obtain the ideal transmission efficiency and comparison. Low noise. In addition, do not hit with a hammer during installation to prevent excessive axial or radial force from damaging the bearings or gears. Be sure to tighten the mounting bolts before tightening the tightening bolts.

The above is the whole content of the spur gear drive application principle, installation method and precautions. Spur gear drives can be used in fields that require high precision such as CNC machine tools and military radars. If you have any questions during the installation or use of the spur gear drive, please call for consultation or leave a message.

What happens if the slewing bearing is improperly lubricated?

When buying slewing bearings, slewing bearing manufacturers will tell us to lubricate the bearings regularly, but for those who don’t understand, improper lubrication may occur during lubrication. Then, are the consequences of improper lubrication of slewing bearings serious? ? What happens if the slewing bearing is improperly lubricated? What should be paid attention to when lubricating bearings?

Consequences of improper lubrication of slewing bearings

Slewing Bearings

1. Discoloration

Metal-to-metal contact will make the bearing temperature too high, causing the raceways and rollers to become discolored. In mild cases, this discoloration is due to the lubricant contaminating the bearing surface, while in severe cases, the metal discolors due to high temperatures. In all cases, early detection can avoid costly repairs.

2. Bearing heating

When the machine is running, the part where the bearing is installed is allowed to have a certain temperature. When touching the housing of the mechanism with your hand, it should be normal that you don’t feel hot, otherwise it indicates that the bearing temperature is too high. One of the reasons for excessively high bearings is poor lubrication of the bearings. The lubricating oil (or grease) used in rolling bearings has a certain working temperature. When the temperature is too high, water or ash enters the bearing seat, it will be seriously oxidized, emulsified, etc., which will lose its lubrication effect and cause the bearing to suffer from high temperature. And burned. In addition, poor quality of lubricating oil (or grease) itself or failure to add oil (grease) during operation will cause the bearing temperature to rise.

3. Scratches and peeling

Inspect the bearing for signs of cutting into the metal or peeling of the metal. These situations require immediate attention. Scratches and peeling are prone to occur in high-load low-speed applications or continuous high temperatures, and thin or insufficient lubricating oil film will accelerate the occurrence of the problem. Insufficient lubrication, wrong grease selection, or sudden changes in working conditions may cause bearing material to peel off or bearing ribs to scratch.

4. Abnormal bearing noise

If the bearing is in a good state of continuous rotation, it will emit a low whining or buzzing sound. If there is a sharp hiss, squeak and other irregular sounds, it often indicates that the bearing is in a poor continuous rotation condition. The sharp squeaking noise may be caused by improper lubrication.

5. The bearing is completely locked

Extreme local heating will produce metal flow in the bearing, changing the original material and geometry of the bearing. This may result in excessive tilting of the rollers, damage to the cage, and complete lock-up of the bearing. If catastrophic damage does occur, it is recommended to consult a bearing expert to determine the root cause of the problem, because it may be a factor other than lubrication.

Precautions for correct lubrication

Slewing Bearings

1. Choose the right grease

Choosing a suitable grease will make the grease fully play the role of lubrication in the bearing operation, so that the bearing can be used for a longer time. The following are the points that need to be paid attention to when choosing the grease. Let’s take a look.

(1) Look at the working temperature: The working temperature of the lubricating part is an important basis for choosing lubricating grease. The typical components that use grease are rolling bearings. Under high temperature conditions, the temperature of the outer ring of the bearing is 15°C lower than the temperature of the inner ring. The temperature of the bearing operating at medium and low speeds (3000-5000r/min) is similar to the temperature of the internal medium. Under low temperature conditions, synthetic oil grease must be used, especially for some instrument miniature bearings, which have a small aerodynamic torque. Pay special attention to the selection of grease.

(2) Look at the running speed of the bearing: the speed of the lubricating component has a great influence on the bearing life of the grease. Therefore, when selecting lubricating grease, the movement speed of the lubricated part must be considered.

(3) Look at the environment: the environment of the lubricating part and the medium in contact have a great influence on the performance of the grease.

(4) Look at the filling method: the filling method of grease includes manual filling and centralized pump filling. Smearing or filling, grease gun filling, grease cup filling, etc. are manual filling and automatic filling.

2. Choose the right way

(1) Manual lubrication: This is a relatively primitive method. In the case of insufficient lubricating oil in the bearing, use an oiler to supply oil. It is usually used for light-load, low-speed or intermittent motion occasions. It is recommended to use the oil filler hole during operation. Dust cover or ball valve is set on it, and felt, cotton, wool, etc. are used as filter devices.

(2) Automatic lubrication: The automatic lubricator is a device used to replace manual refueling. The main advantage of this device is to save labor. It can refuel regularly and quantitatively, so that the life of the equipment can be prolonged, especially suitable for more complicated working conditions. Bottom, can reduce the safety risk of manual refueling. Using an automatic lubricator, you can continuously lubricate the running equipment automatically.

3. Add grease in time

Choosing the appropriate grease and lubrication method is the prerequisite for lubrication, but it is also necessary to add grease in time in daily use. This is also a problem that people often ignore or forget. Adding grease in time is to ensure that the bearing is running to meet the operating conditions Lubricating oil, which is also the key to extending the service life of the bearing.

The above is the whole content of the consequences caused by improper lubrication of the slewing bearing and the lubrication method. We understand that improper lubrication of the slewing bearing may cause the bearing to change color, heat, scratch and peel, have abnormal noise, lock up, etc. When lubricating, pay attention to the correct selection of grease and timely add grease, etc., which can effectively avoid the occurrence of improper lubrication.

What are the maintenance tasks in the use of slewing bearings? How to maintain?

The slewing bearing is an indispensable part of large-scale machinery. It can be installed in the machine to allow the machine to rotate left and right. At the same time, it can withstand various forces. Because the slewing ring is very important, careful maintenance is required. More than 96% of the slewing ring failures are caused by lubrication problems, pollution, wear and incorrect operation, which seriously affects its service life and normal performance.

1. The slewing bearing is coated with a small amount of grease when it leaves the factory. When the product is used, it should be filled with new grease according to different working conditions.

2. The slewing bearing should be greased regularly. According to different types of slewing bearings, the specific grease filling time is as follows:

a: Ball type: Grease is added once every 100 hours of operation.

b; Roller type: Grease is added every 50 hours of operation.

Slewing Bearings

If in a special working environment, such as: tropical, high temperature, dusty, high temperature and continuous continuous work, the grease filling cycle should be shortened, and the grease should be filled once every 50 hours of work; when the gear is working normally, it should be guaranteed to work every time Apply detergent once every 150 hours. When working vigorously, apply detergent once every 75 hours of work. Note that the teeth must be wiped clean before applying detergent. The machine must be refilled with new grease before and after the long-term stagnation of the machine. Each time the grease is added, the raceway must be filled until it overflows from the sealing device. When the grease is added, the slewing ring must be slowly transferred. Make the grease evenly filled in the raceway.

3. Because there are many comprehensive factors in the process of use, the user can choose the grease according to the specific situation. For example, the raceway can use: No. 3, No. 4 graphite grease, industrial grease, No. 203 grease, No. 7002 High and low temperature bearing grease and No. 2 aluminum-based grease, etc.

Since the slewing ring is installed, after 100 hours of operation, the pre-tightening force of the bolts should be checked, and every 500 hours of operation thereafter, it must be adequate and tried.

4. After the equipment has been working for 2000 hours, if a bolt is found to be loose below 80% of the specified torque, the bolt and two adjacent bolts shall be replaced with new ones; if 20% of the bolts are found to be loose to 80% of the specified torque Below, all bolts are replaced with new ones. After the equipment has been working for 14,000 hours, all bolts should be replaced with new ones.

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5. Pay close attention to the operation of the slewing bearing during use. If you find that the noise, impact, or power suddenly increases, you should stop the machine for inspection immediately until all the faults are eliminated, and disassemble and inspect if necessary.

6. When the slewing bearing is in use, it is forbidden to directly wash the slewing bearing with water to avoid water entering the raceway to cause rust; strictly prevent hard foreign objects from approaching or entering the meshing area to avoid injury to the teeth or unnecessary trouble.

7. To keep the surface of the slewing bearing clean, choose a suitable solvent for cleaning according to the surface properties of the rust-proof object, so as to avoid serious corrosion. Surface cleaning can use chemical treatment cleaning method and mechanical cleaning method. When the surface is dry, do a good job in controlling the temperature and wait until most of the area is dry before wiping it with gauze. When applying anti-rust oil, it is necessary to apply different methods according to the different properties of the bearing surface. Miniature bearings can be directly immersed in anti-rust grease. If you encounter a special shape, you can choose the painting method, so that it is not easy to produce accumulation. There are many factors that cause metal corrosion. The chemical composition of the metal itself can also cause corrosion or the temperature and humidity of the environment in which the item exists can also cause corrosion.

8. The sundries on the surface of the slewing ring should be removed frequently during use, and the sealing strips of the slewing ring should be checked for aging, cracking, damage or detachment. If one of these conditions occurs, the sealing strips should be replaced in time to prevent debris and debris from entering the raceway. If the grease is lost, the corresponding grease should be applied after replacement to avoid jamming or rusting of rolling elements and raceways.

The above is a detailed explanation of the maintenance work in the use of the slewing ring. In short, the slewing ring has malfunctions such as noise and impact after a period of use. The operator should pay attention to observe and check in time to eliminate the fault. Only correct and reasonable maintenance of the slewing bearing can ensure its normal operation, give full play to its performance, and extend its service life.

What are the self-locking methods of spur gear drive?

Spur gear drive is also a kind of gear type slewing drive. Its transmission principle is a device in which the pinion drives the gear ring of the slewing ring to rotate and reduce. From the deceleration principle of the slewing drive, we can find that it does not have the self-locking function. Yes, if you want to achieve exact stop, you need to use a brake device for locking. The editor of Ronda will introduce to you the self-locking methods of spur gear drive.

What is spur gear drive self-locking

Spur gear drive self-locking is to manually stop the drive when it needs to be stopped. The main use of the self-locking principle is that when the transmission angle, that is, the complementary angle of the pressure angle, is less than one-half of the friction angle, the conditions for self-locking can be achieved. That is to follow the self-locking phenomenon, when the resultant force of the transmission force of the object acts within the friction angle, no matter how great the force is, there will always be a total reaction force to balance it and keep the object still. However, the spur gear drive cannot achieve self-locking and needs to rely on external force to complete the drive locking effect. The following specifically introduces the ways to realize the self-locking of the spur gear drive.

Self-locking method of spur gear drive

VE Series Slewing Drive

 

1. Servo motor self-locking

When the spur gear slewing drive is driven by a servo motor, when the driving force is small inertia, that is, the starting is frequent and the load is small, the servo motor is usually stopped to achieve the locking of the spur gear drive. The locking force of the servo motor is passed The reduction ratio of the spur gear drive is amplified, and then reflected on the turntable to achieve drive locking. At this time, the locking force is relatively large, which is very suitable for working conditions with small inertia.

2. Self-locking hydraulic motor

The spur gear drive using hydraulic motor can be braked by the hydraulic motor during use, so as to realize the locking of the spur gear drive. Among them, the hydraulic motor braking method is divided into the following three types:

(1) Braking with overflow valve: It can realize bidirectional braking to the hydraulic motor, and can play a buffering effect.

(2) Braking with accumulator: Install accumulators near the oil inlet and outlet of the hydraulic motor to achieve bidirectional braking on the hydraulic motor.

(3) Braking with normally closed brake: When the hydraulic oil in the brake hydraulic cylinder loses pressure, the brake will act immediately to achieve braking.

SDE-PDE SERIES SLEWING DRIVE

3. Self-locking brake reducer

The disc brake that uses the spur gear of the brake reducer to drive the brake motor is installed on the end cover of the motor’s non-output end. When the brake motor is connected to the power supply, the electromagnet attracts the armature and the brake armature is separated from the brake disc and the motor starts When the brake motor loses current, the electromagnet cannot attract the armature, the armature falls back to the brake disc, and the motor stops rotating. The self-locking effect of the spur gear drive is realized through the characteristics of the brake motor’s power-off braking.

4. Bolt brake

What are the self-locking methods of spur gear drive? You can also install a pin hole on the gear drive to lock the spur gear drive that requires a fixed position. At the beginning of the design, a pin hole is designed on the rotating ferrule, and a starter or hydraulic pin device is designed on the frame. During the driving process, the bolt mechanism can pull out the pin to allow the drive to rotate normally. Insert the pin back into the bolt hole at the position where it needs to be stopped and fixed. The drive is fixed on the frame by the pin of the ferrule and cannot rotate. Realize self-locking.

5. Self-locking brake gear

A separate brake gear is installed on the rotary drive. This method is suitable for situations where frequent braking is required and the spur gear drive power is large and the braking power is large. Large braking force will cause the failure of the connection between gears, reduction gears, and motors, and shorten the service life of the spur gear drive. For this reason, the spur gear drive with independent brake gears can be used to achieve separate braking to avoid the transmission force. The connecting parts fail due to the sudden braking, and the parts are damaged.

The above is the main introduction about the self-locking methods of the spur gear drive. The realization of the self-locking function of the slewing drive can be selected according to the specific equipment operating conditions and requirements.

Scrap Standard and Service Life of Tower Crane Slewing Bearing

All machines will suffer loss and failure after a long period of use. When the parts exceed the service life or are damaged beyond repair, they should be scrapped and replaced. The tower crane slewing bearing is prone to failure and damage when subjected to harsh outdoor environments and high-load operation for a long time. So to what extent can it meet the scrap standard of the tower crane slewing bearing?

The scrap standard of tower crane slewing bearing

Slewing Bearings

1. The slewing ring and rolling elements are worn out and scrapped

The wear of raceway ring and rolling element is one of the common forms of slewing bearing scrap. When the raceway pitting corrosion occurs on the surface of the slewing bearing, the surface metal is peeled off and the overall wear is worn, the tower crane will experience abnormal noise, rolling element jamming and excessive clearance between the raceway rings during operation; vibration and local impact will be caused. With the development of the state, the turning resistance will continue to increase and the turning function will be lost.

2. The slewing ring cage is damaged and scrapped

In order to avoid friction between the rolling elements of the tower crane slewing support, an isolator cage is usually added between the rolling elements. The material of the cage is generally copper, plastic, powder metallurgy or mild steel. The cage does not transmit load during the bearing, but it moves with the rolling elements. When the cage is damaged or broken, there will be a sharp and piercing noise. As the broken body of the cage is pushed and crushed by the rotating rolling elements, it will cause serious damage to the raceway ring and rolling elements. At this time, the slewing bearing meets the scrap standard and can be replaced.

3. The slewing ring teeth are damaged and scrapped

The gear meshing mode of the tower crane slewing support has two kinds of external gear meshing and internal gear meshing. When the surface of the gear teeth is excessively worn, cracks and broken teeth appear. The tooth side clearance of the gear teeth of the tower crane slewing bearing is enlarged, and the slewing bearing will immediately lose its function when the tooth is broken and cannot be repaired. At this time, it reaches the scrap standard of the tower crane slewing bearing.

4. The slewing ring connecting bolts are damaged and scrapped

Although the connecting bolt of the slewing ring is not the bearing body, the failure of the bolt will also cause the slewing ring to fail to work. The damage of connecting bolts in tower crane work is also a common phenomenon. When a slewing bearing connecting bolt is loosened or broken, it will often cause a chain reaction to cause the loosening and fracture of other bolts. At this time, the slewing bearing also needs to be replaced.

5. The slewing bearing is damaged and scrapped due to corrosion and burns

Due to the complex working environment of the tower crane slewing bearing, the situation that the bearing may encounter is also unpredictable. If it is corroded by corrosive substances such as acid and alkali during operation, the internal components of the bearing will be damaged and the bearing will be scrapped.

The service life of the tower crane slewing bearing

Slewing Bearings

Under a certain load, the number of revolutions or hours that the bearing experiences before pitting corrosion is called the bearing life. The service life of the tower crane slewing bearing is affected by the speed, radial load, basic rated load, equivalent conformity, speed coefficient, and fatigue life coefficient.

1. Calculation formula of bearing life

L10-When the bearing load is P, the basic rating life (106 revolutions)

C–Basic dynamic load rating N

ε–index

Ball bearing: ε=3

Roller bearing: ε=10/3

P–Equivalent dynamic load (N)

The load on the bearing under actual conditions: A, R, transformed into the load under experimental conditions is called equivalent dynamic load. For bearing components, this load is variable. In the experimental study, the bearing life is changed to 106 The unit is more convenient (counter), but in actual production, the life is generally expressed in hours. For this reason, it must be converted L10×106=Lh×60n

2. Calculation method of tower crane slewing bearing life

(1) Knowing the bearing model, load and shaft speed, calculate Lh;

(2) Knowing the load, speed and expected life, calculate C and select the bearing model.
Usually take the middle repair or overhaul limit of the machine as the design life of the bearing, generally Lh’=5000, and the temperature coefficient ft should be introduced for the bearing working at high temperature

Ct=ftC

t ≤120 125 150 200 300

ft 1 0.95 0.90 0.80 0.60

The above is about the relevant content of the scrap standard of the tower crane slewing bearing. The tower crane’s service life may be affected due to its complicated use environment. At the same time, good maintenance and repair can also extend the service life of the tower crane slewing bearing.