Maintenance and replacement process for variable-amplitude rack of gantry crane
By using the minimum amplitude near-dead point position reinforcement method and safety reinforcement measures in the portal crane, combined with the lifting technology of hand-pulled hoists and wire ropes, efficient and safe replacement of the portal crane's buckle rack is achieved, solving safety hazards and high cost problems in traditional maintenance processes.
Patent Information
- Application Number
- CN202510362195.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-26
- Publication Date
- 2025-05-16
AI Technical Summary
The transmission of the amplitude rack of the door crane is unstable, resulting in serious vibration impact and easy damage to the rack. Traditional maintenance processes have safety hazards, inconvenience and high costs.
The minimum amplitude near-dead point position reinforcement method is adopted for the four-link mechanism of the arm, and the stability after the rack is removed is ensured through safety reinforcement measures. The rack is lifted together with hand-pulled hoists and wire ropes to achieve efficient and safe rack replacement.
It effectively reduces safety hazards during rack replacement, shortens downtime and maintenance time, improves maintenance efficiency and reduces maintenance costs, and is suitable for rack transmission system maintenance in ports, docks and other scenarios.
Smart Images
Figure CN120004133A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of port lifting equipment maintenance, in particular to a process for repairing and replacing a luffing rack of a portal crane. Background Art
[0002] The M40-43 gantry crane (hereinafter referred to as the gantry crane) is a heavy lifting equipment commonly used in berth 11 of Lanshan Port. Its luffing movement usually adopts rack transmission, which has the advantages of simple structure, high transmission efficiency, and easy use and maintenance. However, due to the large meshing clearance between the rack transmission teeth and the drive gear, and the small number of teeth of the drive gear of the gantry crane's luffing mechanism, the meshing of the rack transmission is not smooth enough and the impact is large. Especially when the boom system components of the port gantry crane are large in size and the metal structure is heavy, the crane boom system is prone to large vibration shock during the luffing process, especially when starting, braking and changing the luffing direction, the impact caused is more serious, which is easy to cause damage to the rack.
[0003] There are many shortcomings in the traditional gantry crane rack maintenance and replacement process. On the one hand, the rack is located at a high position on the variable-length platform (such as about 30 meters from the ground) and the variable-length platform space is small, which brings great inconvenience to the maintenance work. On the other hand, the tie rod four-link boom system connected to one end of the rack is huge in weight (such as about 80T) and bears a large load. After the rack is removed, the four-link mechanism loses balance and easily causes the boom to overturn, which will cause a major safety hazard. In addition, the port previously lacked precedents and experience in the maintenance and replacement of 40T gantry crane racks, which increased the difficulty of formulating and implementing the maintenance process plan. If the manufacturer repairs, the maintenance cost is very high and the repair cycle is very long, which will delay the port's production. Therefore, there is an urgent need for a safe, efficient and low-cost maintenance and replacement process for the variable-length rack of a gantry crane to solve the problems existing in the prior art. Summary of the invention
[0004] The purpose of the present invention is to provide a repair and replacement process for a luffing rack of a gantry crane, which can achieve safe and efficient replacement of the luffing rack through an innovative process, thereby reducing repair costs and downtime.
[0005] In order to achieve the above object, the technical solution adopted by the present invention is: A process for repairing and replacing a luffing rack of a portal crane comprises the following steps: Step 1. Find the minimum amplitude near dead point position of the four-bar linkage and take measures to prevent the rod from slipping: reduce the amplitude of the gantry crane's luffing mechanism to the minimum amplitude to ensure that the four-bar linkage is at the near dead point position; connect the wire rope of the opening and closing machine and the left or right machine of the support machine to the lifting lug of the gantry crane's walking end beam, then tighten the wire rope and open the luffing brake to prevent the rod from slipping; Step 2. Strengthen the door operator’s security; 2.1 Strengthen the live counterweight of the balance beam: Use two channel steels to support the two sides of the bottom of the balance beam at the herringbone beam, and use channel steels to weld and reinforce the two sides of the front section of the live counterweight balance beam; 2.2 Strengthen the small tie rod: Weld and reinforce the two sides of the small tie rod of the herringbone frame with I-beams and platform reinforcement beams; Step 3. Remove the front section of the gantry crane rack, the connecting shaft of the boom and the rack pressure wheel; Step 4. Remove the old rack and replace it with a new one; 4.1 Choose the appropriate lifting point and the position of the chain hoist: use two 5T chain hoists and one 3T chain hoist to lift the rack together, hang a 5T chain hoist on the crossbeam of the herringbone tie rod just above the front section of the rack, hang another 5T chain hoist on the pulley base just above the rear section of the rack, and hang a 3T chain hoist between the above two lifting points of the rack; 4.2 Remove the old rack: After the rack is lifted above the rocker arm, use the auxiliary gantry machine to first use a wire rope from the opening and closing machine to hang the rear section of the rack, and then cooperate with the hand chain hoist to move the rack out of the luffing platform; 4.3 Replace the new rack: After the new rack is hoisted to the luffing platform by the auxiliary gantry crane, it is hoisted to the original position by hand chain hoist, which is the opposite of the process of removing the rack; during the hoisting process, pay attention to keep the rack balanced to ensure hoisting safety; 4.4 Install the front shaft of the rack and the upper pressure wheel of the rack: After hoisting the new rack into place, install the front shaft of the rack and the upper pressure wheel of the rack to ensure the correct connection between the rack and the four-bar linkage; Step 5. Remove the reinforcement measures and conduct a test run: After the rack is installed, remove the reinforcement measures at the position of the live counterweight and the small tie rod; after the removal is completed, conduct a test run to check the working status of the rack and the four-bar linkage to ensure the quality of maintenance.
[0006] On the basis of the above technical solution, the present invention can also be improved as follows: As a further improvement of the above technical solution, the amplitude of the gantry crane's amplitude-changing mechanism is the minimum when it is 12 meters, and the boom angle is α=15°±1° when it is at the near dead point position.
[0007] As a further improvement of the above technical solution, the herringbone beam is supported by two 85cm long and 150mm wide channel steels, one on each side of the bottom of the balance beam, and one 280cm long and 180mm wide channel steel is welded and reinforced on both sides of the front section of the live counterweight balance beam.
[0008] As a further improvement of the above technical solution, both sides of the small tie rod of the herringbone frame are welded and reinforced with 100x150mm I-beams and platform reinforcement beams.
[0009] As a further improvement of the above technical solution, in step 3, a special maintenance gantry is made, the position is adjusted, and a jack is installed for top pressure removal, and the jack uses a 200T hydraulic jack.
[0010] As a further improvement of the above technical solution, in step 4, after the rack is moved out of the variable amplitude platform, a wire rope of the gantry crane support machine is used to hang the front section of the rack, and then the gantry crane is rotated and the amplitude is retracted to hang the rack down for replacement of the tooth plate for maintenance.
[0011] Compared with the prior art, the present invention has the following beneficial effects: 1. The method of reinforcing the position of the minimum amplitude near the dead point of the boom to replace the variable-length rack: The present invention uses the minimum amplitude near the dead point of the four-bar linkage mechanism of the gantry crane boom to reinforce it as the best solution for hoisting and repairing the gantry crane rack. By finding the near dead point of the four-bar linkage mechanism for reinforcement, the safety hazard after the rack is removed is effectively reduced, and the downtime for maintenance is controlled within 12 hours, which reduces the downtime of the gantry crane and improves the maintenance efficiency. It is suitable for safe and efficient maintenance of the rack transmission system in ports, docks and other scenes; 2. Adopt safety reinforcement measures: Before removing the rack, the balance beam live weight and small pull rod are safely reinforced to ensure stability during the removal process; the reinforcement measures are simple and effective, reducing maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The present invention is further described below in conjunction with the accompanying drawings and embodiments.
[0013] Figure 1 It is a flow chart of a maintenance and replacement process of a luffing rack of a portal crane provided by a preferred embodiment of the present invention; Figure 2 and Figure 3 It is the on-site construction drawing of reinforcing the live counterweight of the balance beam; Figure 4 This is the on-site construction drawing for reinforcing the small tie rod; Figure 5 It is the on-site construction drawing of dismantling the front section of the gantry crane rack and the connecting shaft of the big arm and the rack pressure wheel; Figure 6 and Figure 7 This is the on-site construction drawing of using a hand winch to bolt and hang the rack. DETAILED DESCRIPTION
[0014] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0015] 1. Preparation before maintenance Data review and plan formulation: First, review the relevant structural data of the gantry crane to understand the structural characteristics and working principles of the rack, four-bar linkage and other components. At the same time, learn from the manufacturer's previous gantry crane small tie rod bearing replacement process and other models of gantry crane rack replacement process, combined with the actual structural characteristics of the gantry crane, after many discussions and studies, a detailed maintenance process flow was formulated.
[0016] Identification of hazardous factors and formulation of safety measures: Based on the details of each step in the maintenance process, possible hazardous factors in the operation are identified and discussed, and corresponding safety measures are formulated to ensure the safety of personnel and equipment during the maintenance process.
[0017] Preparation of tools and materials: According to the maintenance process, prepare the required tools, materials and equipment, including hand hoists, wire ropes, channel steels, I-beams, jacks, special maintenance gantries, etc.
[0018] 2. Maintenance implementation steps like Figures 1 to 7 As shown, a preferred embodiment of the present invention provides a process for repairing and replacing a luffing rack of a portal crane, comprising the following steps: Step 1. Find the position of the minimum amplitude near the dead point of the four-bar linkage and take measures to prevent the rod from slipping; Reduce the amplitude of the gantry crane's luffing mechanism to the minimum amplitude, and ensure that the four-bar linkage is in the near-dead point position; connect the wire rope of the opening and closing machine and the left or right machine of the supporting machine to the lifting lug of the gantry crane's walking end beam, and then tighten the wire rope and open the luffing brake to ensure that the rod does not slip; in this embodiment, the amplitude of the gantry crane's luffing mechanism is the minimum amplitude when it is 12 meters, and the arm angle is α=15°±1° when it is in the near-dead point position.
[0019] Step 2. Strengthen the door operator’s security; 2.1 Strengthen the live counterweight of the balance beam: Use two channel steels to support the two sides of the bottom of the balance beam at the herringbone beam, and use channel steels to weld and reinforce the two sides of the front section of the live counterweight balance beam; Since the live counterweight and the boom form a dynamic balance with the rack during the luffing movement, this balance will be broken after the rack is removed, which may cause the boom system to slip and cause a safety hazard. Therefore, before removing the rack, the live counterweight must be supported and reinforced in a reliable position. The live counterweight and the balance beam weigh about 60T. Directly below the live counterweight is the ceiling of the machine room, which is a 5mm thick steel plate that cannot bear weight and can only be supported and reinforced at the herringbone beam. Specifically, at the herringbone beam, two 85cm long and 150mm wide channel steels are supported on each side of the bottom of the balance beam, and one 280cm long and 180mm wide channel steel is welded and reinforced on both sides of the front section of the live counterweight balance beam (such as Figure 2 , Figure 3 as shown).
[0020] 2.2 Strengthen the small tie rod: Weld and reinforce the two sides of the small tie rod of the herringbone frame with I-beams and platform reinforcement beams; In order to fix the arm system after the rack is removed, it is necessary to find the best position to fix the small tie rod of the A-frame. Specifically, the two sides of the small tie rod of the A-frame are welded and reinforced with 100x150mm I-beams and platform reinforcement beams (such as Figure 4 as shown), to ensure the stability of the boom system after the rack is removed.
[0021] Step 3. Remove the front section of the gantry crane rack, the connecting shaft of the boom and the rack pressure wheel; Since the rack is subject to the balanced load of the gantry crane's four-bar linkage, the front section of the rack and the connecting shaft of the boom are subject to a large load, making it difficult to dismantle. A special maintenance gantry can be made according to the situation, the position can be adjusted, and a jack can be installed for top pressure removal. A 200T hydraulic jack can be used as the jack.
[0022] Step 4. Remove the old rack and replace it with a new one; 4.1 Choose the appropriate lifting point and the position of the chain hoist: Use two 5T chain hoists and one 3T chain hoist to lift together. Hang a 5T chain hoist on the crossbar of the herringbone tie rod just above the front section of the rack, and hang another 5T chain hoist on the pulley base just above the rear section of the rack. In other words, the front section of the rack lifting point is located at the crossbar of the herringbone tie rod just above the front section of the rack, and the rear section of the rack lifting point is located at the pulley base just above the rear section of the rack. Hang a 3T chain hoist between the above two lifting points of the rack; the main function of the two 5T chain hoists is to lift the rack and lift it off the rocker frame; the main function of the 3T chain hoist is to adjust the front and rear direction of the rack; 4.2 Remove the old rack: After the rack is lifted above the rocker arm, use the auxiliary gantry machine to first use a wire rope from the opening and closing machine to hang the rear section of the rack, and then cooperate with the hand chain hoist to move the rack out of the luffing platform; After the rack is moved out of the variable amplitude platform, a wire rope of the gantry crane support machine is used to hang the front section of the rack, and then the rack is lowered to replace the tooth plate for maintenance in coordination with the gantry crane rotation and amplitude reduction. During the hoisting process, it is important to note that the wire rope used to cooperate with the gantry crane hoisting should be a support machine wire rope and a switch machine wire rope, which is conducive to maintaining the balance of the rack and ensuring hoisting safety.
[0023] 4.3 Replace the new rack: After the new rack is hoisted to the luffing platform by the auxiliary gantry crane, it is hoisted to the original position by hand chain hoist, which is the opposite of the process of removing the rack; during the hoisting process, pay attention to keep the rack balanced to ensure hoisting safety; 4.4 Install the front shaft of the rack and the upper pressure wheel of the rack: After hoisting the new rack into place, install the front shaft of the rack and the upper pressure wheel of the rack to ensure the correct connection between the rack and the four-bar linkage; Step 5. Remove the reinforcement measures and test run; After the rack is installed, remove the reinforcement measures of the live counterweight position and the small pull rod; after the removal is completed, conduct a test run to check the working status of the rack and four-bar linkage to ensure the quality of maintenance.
[0024] 3. Technological innovation 1. The method of reinforcing the position of the minimum amplitude near the dead point of the boom to replace the variable-length rack: The present invention uses the minimum amplitude near the dead point of the four-bar linkage mechanism of the gantry crane boom to reinforce it as the best solution for hoisting and repairing the gantry crane rack. By finding the near dead point of the four-bar linkage mechanism for reinforcement, the safety hazard after the rack is removed is effectively reduced, and the downtime for maintenance is controlled within 12 hours, which reduces the downtime of the gantry crane and improves the maintenance efficiency. It is suitable for safe and efficient maintenance of the rack transmission system in ports, docks and other scenes; 2. Adopt safety reinforcement measures: Before removing the rack, the balance beam live weight and small pull rod are safely reinforced to ensure stability during the removal process; the reinforcement measures are simple and effective, reducing maintenance costs.
[0025] If the gantry crane manufacturer repairs it, each gantry crane will require a repair cost of about 60,000 yuan and take about three days. Five gantry cranes in our port have experienced this kind of failure. Now one gantry crane has been repaired and replaced. This can reduce the outsourced repair cost of each gantry crane by about 60,000 yuan. After all repairs are completed, the repair cost can be saved by about 300,000 yuan and the repair time can be reduced by about 96 hours. Calculated at 300 tons of cargo per hour, the cargo loading and unloading capacity can be increased by 28,800 tons.
[0026] The gantry crane rack was repaired and replaced by the above process, achieving the expected goal and completing the emergency repair task safely and smoothly, which not only trained the maintenance team but also ensured the smooth operation of the port production. It not only improved the maintenance innovation level of employees and improved the maintenance efficiency, but also accumulated valuable experience for the next related maintenance of the same model gantry crane.
[0027] Any details not mentioned in the above specific embodiments of the present invention belong to the known technologies in the art and can be implemented with reference to the known technologies.
[0028] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.
Claims
1. A process for repairing and replacing a luffing rack of a portal crane, comprising the following steps: Step 1. Find the minimum amplitude near dead point of the four-bar linkage and take measures to prevent the rod from slipping: reduce the amplitude of the gantry crane's luffing mechanism to the minimum amplitude to ensure that the four-bar linkage is at the near dead point; connect the wire rope of the opening and closing machine and the left or right machine of the support machine to the lifting lug of the gantry crane's walking end beam, then tighten the wire rope and open the luffing brake to prevent the rod from slipping; Step 2. Strengthen the door operator’s security; 2.1 Strengthening the live counterweight of the balance beam: Use two channel steels to support the two sides of the bottom of the balance beam at the herringbone beam, and use channel steels to weld and reinforce the two sides of the front section of the live counterweight balance beam; 2.2 Reinforce the small tie rod: Weld and reinforce the two sides of the small tie rod of the herringbone frame with I-beams and platform reinforcement beams; Step 3. Remove the front section of the gantry crane rack, the connecting shaft of the boom and the rack pressure wheel; Step 4. Remove the old rack and replace it with a new one. 4.1 Choose the appropriate lifting point and the position of the chain hoist: Use two 5T chain hoists and one 3T chain hoist to lift the rack together, hang a 5T chain hoist on the crossbeam of the herringbone tie rod just above the front section of the rack, hang another 5T chain hoist on the pulley base just above the rear section of the rack, and hang a 3T chain hoist between the above two lifting points of the rack; 4.2 Remove the old rack: After the rack is lifted above the rocker arm, use the auxiliary gantry crane to first use a wire rope from the opening and closing machine to hang the rear section of the rack, and then cooperate with the hand winch to move the rack out of the luffing platform; 4.3 Replace the new rack: After the new rack is hoisted to the luffing platform by the auxiliary gantry crane, it is hoisted to the original position by hand chain hoist, which is the opposite of the process of removing the rack; during the hoisting process, pay attention to keep the rack balanced to ensure hoisting safety; 4.4 Install the front shaft of the rack and the upper pressure wheel of the rack: After hoisting the new rack into place, install the front shaft of the rack and the upper pressure wheel of the rack to ensure the correct connection between the rack and the four-bar linkage; Step 5. Remove the reinforcement measures and conduct a test run: After the rack is installed, remove the reinforcement measures at the position of the live counterweight and the small tie rod; after the removal, conduct a test run to check the working status of the rack and the four-bar linkage to ensure the quality of maintenance.
2. The process for repairing and replacing the luffing rack of a gantry crane according to claim 1 is characterized in that: The gantry crane luffing mechanism has a minimum luffing amplitude of 12 meters, and the boom angle is α=15°±1° when it is at the near dead point position.
3. The process for repairing and replacing the luffing rack of a gantry crane according to claim 2 is characterized in that: The herringbone beam is supported by two 85cm long and 150mm wide channel steels, one on each side of the bottom of the balance beam, and is welded and reinforced by one 280cm long and 180mm wide channel steel on each side of the front section of the live counterweight balance beam.
4. The process for repairing and replacing the luffing rack of a portal crane according to claim 3 is characterized in that: The two sides of the small tie rod of the herringbone frame are welded and reinforced with 100x150mm I-beams and platform reinforcement beams.
5. The process for repairing and replacing the luffing rack of a portal crane according to claim 4 is characterized in that: In the step 3, a special maintenance gantry is made, the position is adjusted, and a jack is installed for top pressure removal, and a 200T hydraulic jack is used as the jack.
6. The process for repairing and replacing the luffing rack of a portal crane according to claim 1 is characterized in that: In step 4, after the rack is moved out of the variable amplitude platform, a wire rope of the gantry crane support machine is used to hang the front section of the rack, and then the rack is lowered to replace the tooth plate for maintenance in coordination with the rotation and retraction of the gantry crane.