The single cylinder hydraulic cone crusher is composed of a dynamic cone liner, a fixed cone liner, a bottom oil cylinder, and transmission gears to form a crushing system. Divided into two rack shells, the shells are connected by bolts (Figure 1).
Figure 1 Single cylinder hydraulic cone breaking structure diagram
1. Question:
During the operation of the crusher, elastic materials such as sleepers and rubber are often mixed into the raw ore. As a result, pure ore is easily crushed in the crushing chamber of this type of cone crusher, while elastic materials cannot be crushed and cannot be unloaded or stopped due to the inability to reach the preset unloading pressure. The moving cone is often stuck in the crushing chamber and repeatedly squeezed, resulting in abnormal wear of the top bearing of the upper bracket. The eccentric copper sleeve under the moving cone runs off center and is severely worn, even burned and blackened, which seriously affects production. This article mainly analyzes the problem and finds countermeasures.
2. Reason for top bearing failure
The top bearing of the cone crusher is a GE260ES joint bearing with an inner diameter of d=260mm, an outer diameter of D=370mm, and a thickness of B=150mm (Figure 2).
Figure 2 Structural diagram of joint bearing
The top bearing is composed of an inner ring with an outer spherical surface and an outer ring with an inner spherical surface, which can withstand large loads. Can withstand radial loads, axial loads, or combined radial and axial loads simultaneously. This bearing is generally used for low-speed swinging motion and can also perform tilting motion within a certain angle range. It is installed in this type of crusher, with the outer ring fixed to the bearing hole seat. During swinging motion, the central shaft sleeve and the inner ring move up and down, and the outer arc surface of the inner ring rotates relative to the inner arc surface of the outer ring.
2.1 Destruction of self-lubricating cushion layer
There is a self-lubricating pad layer between the inner and outer rings of the joint bearing. When the contact pressure exceeds the allowable range, the friction coefficient and wear of the bearing increase with the change of swing frequency. Under the action of swing frequency and contact pressure, the pad material undergoes plastic deformation, compression deformation, and detachment, and the inner ring material transfers to the pad, causing the self-lubricating ability of the joint bearing pad to decrease, resulting in adhesive wear and abrasive wear of the pad material and failure.
2.2 Periodic load impact
In the working environment of ore crushing, due to the presence of other impurities in the upstream ore, the crusher often experiences overload, causing the bearings to bear impact loads. At the same time, under long-term rotational loads, when the load stress exceeds the material yield limit, the bearing ring is eroded, resulting in increased clearance between the inner and outer rings of the joint bearing, severe vibration, increased wear, and operation failure. In severe cases, the bearing may fail.
2.3 Poor sealing
Both the upper and lower sections of the top bearing are equipped with dust-proof sealing devices. The upper part is covered by an upper shaft cover for sealing, and the lower part is equipped with a V-shaped lip dust-proof sealing ring. This sealing ring is mainly used to prevent mineral dust and debris from entering the top bearing and damaging the inner and outer surfaces of the top bearing. Due to long-term operation, the strength of the sealing ring deteriorates, the elasticity decreases, and the wear resistance decreases. When the main shaft moves back and forth, when the external torque generated by the main shaft and the sealing ring is greater than the anti torque torque torque of the sealing ring itself, the sealing ring will flip around or partially. At the same time, it is easy to cause root wear and gap bite, which allows mineral dust and debris particles to enter the top bearing and damage the moving surface of the top bearing, causing damage to the ring raceway. Failure due to indentation.
2.4 Inadequate lubrication
Although the top bearing has a self-lubricating cushion layer, due to its harsh working environment and poor sealing, it is often necessary to inject lubricating grease into the top bearing area on time and in the appropriate amount to isolate the contact between the self-lubricating cushion layer and mineral dust particles, promote better lubrication of the top bearing, and extend the bearing life. Once the lubricating grease is not added in a timely manner or in a small amount, the mineral dust particles that enter are easily attached to the surface of the top bearing, forming abrasive particles and damaging the self-lubricating cushion layer. At the same time, the old lubricating grease will mix with the mineral dust, deteriorate and harden, accelerate bearing wear, and affect bearing activity performance, leading to the failure of the top bearing.
3. The impact of top bearing failure on crusher
This single cylinder hydraulic cone crusher is a bottom single cylinder hydraulic crusher with two support points on the moving cone central axis. The upper fulcrum is located at the lower mouth of the top bearing, and the lower fulcrum is located at the top of the ball bearing at the lower end of the central shaft. During normal operation, the lower pivot point of the central axis is in a pendulum motion relative to the upper pivot point. The trajectory is a spherical trajectory with the upper pivot point as the center of rotation and the distance between the two pivot points as the radius, while the upper pivot point is actually in a circular motion around the centerline of the crossbeam.
Once the top bearing fails, it loses the function of automatic centering of the suspension. When the equipment is running, the top bearing will be subjected to the squeezing force of the dynamic cone and move irregularly in all directions of the horizontal plane. That is, the regular circular motion trajectory of the upper support point will be destroyed, resulting in a constant change in the radius (distance between support points), which leads to irregular swinging motion of the central shaft. This causes the contact points between the central shaft and the copper sleeve to be intermittent, and there are few contact points and high stress at the thick edge of the eccentric copper sleeve, exceeding the strength of the oil film, causing the oil film to rupture and dry friction to occur.
Dry friction causes a sharp increase in temperature at the contact point, and the high temperature at the contact point is transmitted to the entire eccentric copper sleeve. When the temperature reaches a certain level, due to the fact that the copper sleeve material is tin green copper, its coefficient of thermal expansion is higher than that of the eccentric steel sleeve, causing the copper sleeve to expand outward when heated to a certain limit. After being restrained by the inner circular surface of the steel sleeve, the copper sleeve expands inward again? In severe cases, cracks appear on the inner surface and the copper sleeve exhibits a "shaft hugging" phenomenon. Meanwhile, lubrication? By blocking the circulation channel through the inner wall of the copper sleeve, lubricating oil cannot form a circulation loop and enter the oil tank for cooling. Due to heat transfer, the oil temperature suddenly increases. When the oil temperature exceeds a certain temperature, the contact area of the "holding shaft" will experience a "burning black" phenomenon.
4. Handling measures
4.1 Check the integrity of the top bearing hole seat structure
Check the structural integrity of the top bearing installation on the support crossbeam of the crusher, inspect whether the support crossbeam is deformed, whether the bearing hole base sinks, and whether there are cracks around it. If it is a repairable defect that does not affect the use effect, it should be repaired in a timely manner to prevent the defect from expanding. Otherwise, the support should be replaced.
4.2 Check the wear of the central shaft sheath and top bearing
When the failure is due to the clearance between the inner and outer rings of the bearing exceeding the allowable range, it is generally manifested as scratches, and a new bearing should be replaced; When the gap between the inner ring and the center shaft sleeve exceeds the allowable value of 1.5mm, it should be checked separately for wear on the center shaft sleeve and the inner ring of the bearing. If the outer diameter of the center shaft sleeve is less than 259.25mm, the center shaft sleeve should be replaced. If the inner ring diameter of the bearing is less than 260mm, the top bearing should be replaced.
4.3 Clean the debris in the top bearing hole seat to ensure that the oil injection hole is unobstructed
Clean the mineral dust and grease mixture or other debris inside the top bearing hole seat, and confirm whether the upper and lower oil injection holes are connected to the bearing hole seat by conveying high-pressure gas or local heating. If they are not connected, the grease injection hole and oil injection pipe should be unblocked.
4.4 Use reasonable methods to repair the top bearing hole seat
When the failure mode is the top bearing "running outer ring", the top cover bearing hole seat should be repaired. If the unilateral wear is less than 1.5mm, spraying method can be used; If the single-sided diameter is greater than 1.5mm, the method of expanding the hole and inserting the sleeve is selected. Firstly, the bearing hole seat of the top cover is expanded to 410mm to ensure that the single-sided wall thickness of the bowl shaped seat of the upper support beam is greater than 30mm. Steel materials with strong rigidity and high hardness are selected, and the structural features meet the assembly requirements. The outer diameter is 410mm, with an upper deviation of+0.15mm and a lower deviation of+0.10mm; A cylindrical sleeve with an inner diameter of 370mm, an upper deviation of+0.08mm, and a lower deviation of+0.05mm, and a hot fitting hole seat.
4.5 Install strictly in accordance with the installation sequence and requirements
Install according to the installation sequence, first install the V-shaped lip dust seal ring, ensuring that the lip is facing downwards, and then install the top bearing. When installing the top bearing, it should be installed with moderate pressure according to the requirements, pre lubricated, and ensure that the sealing ring lip does not turn over or bite.
5. Prevention and maintenance suggestions
5.1 Set up filtering devices to improve mineral purity
To prevent underground foreign objects such as iron blocks, wood, rubber, etc. from being carried in the ore feed, foreign objects must be removed in a timely manner. At the same time, according to the particle size of the crushed minerals in the intermediate crushing machine, a foreign object filtering device should be installed between the intermediate crushing and the fine crushing belt transportation process to prevent foreign objects from entering the crushing chamber of the cone crusher.
5.2 Strengthen the inspection of top bearings and corresponding contact parts
Check whether the clearance between the inner and outer rings of the top bearing exceeds the tolerance range and whether the bearing hole seat is worn. If there is only noise during idle operation, it indicates that the top bearing or main shaft sleeve is worn and needs to be dealt with in a timely manner. Under normal operation, the central shaft sleeve is also replaced once a year. When replacing the top bearing, due to its special nature, not only should the model be confirmed to be correct, but also the authenticity of the bearing should be identified.
5.3 Proper maintenance and operation
Under normal operation of the equipment, the operator should strictly follow the operating requirements and inject about 50g of lubricating grease every 8 hours. During each injection process, the oil pipe should be carefully checked for smoothness, blockage, and whether the lubricating grease is truly injected into the oil chamber to ensure the lubrication effect of the top bearing.
5.4 Ensure even ore separation and improve the impact of ore feeding
Design a ore separator based on the characteristics of the cone crusher funnel and upper shaft cover, to solve the problems of concentrated ore in a certain part of the lower ore funnel, uneven feeding of ore into the crushing chamber, uneven radial force on the moving cone, and severe deviation. If conditions permit, the height of the ore hopper between the ore hopper and the crusher should be reduced to within 1.5m or a small buffer ore bin should be installed above the crusher to reduce the gravity impact of the ore on the crusher, especially on the upper support beam and the moving cone.
2025 January 2nd Week VAFEM Product Recommendation:
Water pump bearings are double row bearings and, in contrast to conventional double row bearings, do not have an inner ring but raceways machined directly into the surface of the shaft.
As a precious high quality water pump bearings manufacturer and supplier in China, VAFEM can guarantee the quality and precision of the products through complete testing technology and advanced equipment. Please come to buy water pump bearings at the best price and quality from VAFEM. Please contact us for any questions!
https://www.vafem.com/products/Water-Pump-bearings/847.html
As a precious high quality wheel hub bearings manufacturer and supplier in China, VAFEM can guarantee the quality and precision of the products through complete testing technology and advanced equipment. Please come to buy wheel hub bearings at the best price and quality from VAFEM. Please contact us for any questions!
2025-01-10