01. Equipment Introduction
A company's first line ф 4m × 60m new dry process cement production line has been put into operation since July 2003. Three speed support, single transmission, with a slope of 4% (sine), the kiln body rotates clockwise when viewed from the kiln head to the kiln tail, and its main component layout is shown in Figure 1.
Figure 1 Main components of rotary kiln
Figure 2 Structural diagram of hydraulic gear wheel three bearing system
The rotary kiln adopts a single hydraulic stop wheel device to control the up and down operation of the kiln. The hydraulic stop wheel is a three bearing system as shown in Figure 2.
02. Fault details
In April 2019, during on-site inspection, it was found that one bolt on the bottom cover of the hydraulic gear wheel was broken. Immediate measures were taken to add a round steel pad to the lower part of the bottom cover, and the operation was continuously monitored.
In July 2019, the central control operator noticed a gradual increase in kiln current and immediately notified relevant personnel to investigate the cause. On site, it was found that the hydraulic stop wheel was stuck and unable to rotate, with scratches on the contact surface of the stop wheel and 5 broken bottom cover bolts; Subsequently, the production and kiln speed were gradually reduced, and the material was stopped for temporary maintenance. The hydraulic stop wheel was replaced.
After inspection of the hydraulic gear wheel, the M20 × 60 bolt on the bottom cover was broken, and the contact surface of the gear wheel was scratched and tilted, causing one end to rub against the hydraulic gear wheel cylinder. The labyrinth between the bottom of the mushroom head and the base was worn and iron shavings were pulled out; After disassembling the hydraulic gear wheel, it was found that the lower thrust bearing (29326), retaining frame, rollers, and other components of the gear wheel were all broken, while the other two sets of double row roller bearings were better; The bottom maze edge of the mushroom head and the surface of the base maze are severely worn.
03. Take measures
Through force analysis, it is preliminarily judged that the deviation between the centerline of the hydraulic stop wheel and the centerline of the kiln is too large. Due to the lack of professional instruments, the offset cannot be accurately determined. During the installation and adjustment process, close attention should be paid to the contact situation of the force surface of the hydraulic stop wheel; In this installation, the centerline of the hydraulic gear wheel is moved 3mm towards the rotating end to reduce the force on the gear wheel; Remove the loose parts of the foundation through secondary grouting and re tighten the inner cushion plate; When removing the hydraulic gear wheel for repair, replace the manufacturer's original hexagon socket bolt M20 × 60 with M24 × 60 bolt, and the inner hole should be milled flat to increase the contact surface.
After reinstalling the hydraulic stop wheel and running for a period of time, the hydraulic stop wheel still has irregular slight shaking. The hydraulic stop wheel oil station displays a pressure of 5-6MPa, and the hydraulic stop wheel vibrates when the kiln operating conditions fluctuate. In October 2019, a centerline inspection was conducted on the rotary kiln, and it was found that there was a serious deviation between the axis of the hydraulic stop wheel and the kiln centerline, with a deviation of 10mm towards the screw in side, as shown in Figure 3, which seriously exceeded the specified range. Installation specifications: The gear wheel device should be biased towards the rotating side of the wheel belt relative to the kiln centerline, with a deviation of 2-5mm (different manufacturers have different regulations, and there are also regulations that bias towards the rotating side of 0-5mm).
Figure 3 Deviation between the axis of the hydraulic gear wheel and the kiln axis
Figure 4: The hydraulic gear wheel moves 8mm towards the spin out side (left side)
Immediately adjust the hydraulic stop wheel and move it 8mm towards the spin out side (left side), as shown in Figure 4.
After adjustment, the hydraulic gear wheel runs normally, and the hydraulic gear wheel oil station shows a pressure drop from 5MPa to 2MPa, and it has been running smoothly until now.
04. Cause analysis
The hydraulic gear shift is too large. From the record check, it can be seen that the main reason is that when dealing with the vibration of the large gear during operation, the adjustment of the third gear support wheel is not very standardized. Sometimes only one side is adjusted, and the adjustment record data shows that the deviation is not significant. However, due to changes in force, wear of the support wheel, and other reasons, the actual kiln centerline offset size has exceeded the recorded size; Excessive offset causes high stress on the lower bearing and bottom cover bolts of the hydraulic gear wheel.
The blocking wheel and the wheel belt generally make a conical inclined contact. Under normal working conditions, the positive pressure perpendicular to the contact surface will generate a vertical downward force, and the wheel belt will apply a downward pressure Fy to the blocking wheel device (see Figure 5); At the same time, during installation, it is required that the stop wheel device be biased towards the rotating side of the wheel belt relative to the kiln centerline, with an offset of 2-5mm, to ensure that the force exerted by the wheel belt on the stop wheel is always downward.
Figure 5: Force exerted by the wheel belt on the blocking wheel
But when the installation position of the blocking wheel is incorrect, the centerline of the blocking wheel device is biased towards the spinning out side of the wheel belt, or too biased towards the spinning in side, or the centerline of the kiln is bent and deformed; When the wheel belt rotates, it will be equipped with a stop wheel upwards or downwards (in addition, uneven wear and grooves on the contact surface between the stop wheel and the wheel belt may cause the stop wheel device to be pulled up or pressed down when the wheel belt rotates).
The hydraulic stop wheel of the company's # 1 kiln is too biased towards the screw in side, causing excessive downward force on the stop wheel when the wheel belt rotates, resulting in excessive force on the bottom thrust shaft of the hydraulic stop wheel, which in turn causes a series of problems such as bolt breakage and bearing damage on the bottom cover; After translational adjustment, there have been no incidents of bottom cover bolt breakage or bearing damage during the operation of the hydraulic gear wheel.
05. Conclusion
When installing the gear wheel, it is necessary to grasp the key dimensions and control the deviation range, such as the contact length between the gear wheel and the wheel belt, the slope of the gear wheel, and the lateral offset of the gear wheel. After being put into operation, regular measurements and inspections should be carried out, such as whether the deviation of the kiln centerline exceeds the standard, whether the offset between the stop wheel and the kiln centerline is within the specified range, whether the inclination of the base is normal, and whether the connecting bolts at all places are loose; When the large gear vibrates, try to adjust the supporting wheels on both sides together as much as possible. If it exceeds the specified range, it must be corrected in a timely manner, otherwise it will affect the subsequent operation? A series of problems will arise.
2025 June 3rd Week VAFEM Product Recommendation
VAFEM Hub units are designed to allow rear wheels, especially in passenger cars, to turn on an axle even under heavy loads.
Features:
magnetic, electric, and mechanic ABS
with and without ABS
flange only
Steel Material: GCr15/52100/100Cr6
Steel Type: Forged
Ball Grade: G10
Grease: Shell
2025-06-20