Method for preventing water from entering the crankcase of a horizontal plunger pump for descaling rolling mills

Abstract

This invention relates to a method for preventing water ingress into the crankcase of a horizontal plunger pump used for descaling in steel rolling, belonging to the field of medium and heavy plate production technology in the metallurgical industry. The technical solution is as follows: a water baffle (1) and a packing seal structure (8) are respectively installed on the plunger (2) between the plunger (9) and the plunger head (10) of the plunger pump. The water baffle (1) is trumpet-shaped, with its opening facing the plunger head (10). The packing seal structure (8) includes a packing gland (3), a packing box (4), a support sleeve (5), and a packing assembly (6). The packing box (4) is fixed to the plunger head (10), and a packing gland (3) and alternating support sleeves (5) and packing assemblies (6) are installed on the plunger (2) inside the packing box (4). The beneficial effects of this invention are: it can prevent water ingress into the crankcase, eliminate equipment failures such as lubricating oil emulsification and component damage caused by water ingress into the crankcase, and reduce packing wear, thus extending the service life of the plunger pump.

Description

Technical Field

[0001] This invention relates to a method for preventing water from entering the crankcase of a horizontal plunger pump used for descaling in steel rolling, belonging to the technical field of medium and heavy plate production equipment in the metallurgical industry. Background Technology

[0002] The descaling system of medium and heavy plate production lines typically uses a horizontal plunger pump as the descaling pump. This plunger pump is a reciprocating volumetric pump, mainly consisting of a crankcase, plunger, and pump head. The plunger reciprocates through the eccentric rotation of the crankshaft within the crankcase, achieving the intake and discharge of descaling water. The plunger section of the plunger pump is sealed with a packing assembly. Due to the high-speed reciprocating motion of the plunger during operation, the packing is prone to wear, leading to water leakage during the plunger's internal thrust. The leaked water splashes with the plunger's movement and is carried into the crankcase when the crankshaft pulls the plunger back. Water ingress into the crankcase can trigger a series of equipment malfunctions: causing rust in the oil tank, emulsification of the lubricating oil, disruption of the oil film structure during crankshaft rotation, increased friction between the crankshaft bearings, journals, and crankshaft journals, leading to severe wear of the crankshaft journals, bearings, and journals, and even causing a major plunger pump accident.

[0003] Repairing crankcase water ingress accidents is a complex process, requiring the removal of the crankshaft, plungers, bearings, and bushings; a thorough cleaning of the crankcase; and replacement or repair of damaged parts. The repair cycle is at least four days, resulting in significant losses in labor and spare parts costs, as well as unplanned production line downtime, severely impacting the continuous and stable operation of steel rolling. Currently, there is no targeted comprehensive protection method to solve the aforementioned crankcase water ingress problem; therefore, an integrated solution is needed that addresses prevention at the source, structural optimization, and standardized operation and maintenance. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preventing water ingress into the crankcase of a horizontal plunger pump used for descaling in steel rolling mills. This method can prevent water ingress into the crankcase, eliminate equipment malfunctions such as lubricating oil emulsification and component damage caused by water ingress into the crankcase, reduce packing wear, extend the service life of the plunger pump, and solve the problems existing in the background art.

[0005] The technical solution of this invention is: A method for preventing water ingress into the crankcase of a horizontal plunger pump used for descaling in steel rolling mills involves installing a water baffle and a packing seal structure on the plunger between the crankcase and the pump head. The packing seal structure includes a packing gland, a packing box, a support sleeve, and a packing assembly. The packing box is fixed to the pump head, and the plunger inside the packing box is provided with a packing gland and alternating support sleeves and packing assemblies.

[0006] The water baffle is funnel-shaped, with its opening facing the plunger pump head.

[0007] The water-blocking cover is fixed to the plunger by stainless steel clamps.

[0008] The support sleeve is a nylon sleeve or a bakelite sleeve, and the support sleeve is precisely fitted to the outer surface of the plunger.

[0009] The inner hole of the support sleeve has a surface finish of grade 6 and a roughness of Ra1.6.

[0010] The packing assembly consists of aramid graphite open rings, with the cuts of two adjacent aramid graphite open rings at 180° or 120° to each other.

[0011] The stuffing box is provided with a circular hole that mates with the plunger, support sleeve and packing assembly.

[0012] The beneficial effects of this invention are: (1) Thorough protection effect: Through physical isolation, structural optimization and operation and maintenance standards, protection is formed from multiple dimensions such as the source of leakage, transmission path and equipment wear, which completely solves the technical problem of water ingress into the crankcase and eliminates equipment failures such as lubricating oil emulsification and component wear caused by water ingress. (2) Extended equipment life: The support sleeve alleviates packing wear, reduces friction loss between the plunger and the packing, significantly extends the service life of key components such as packing, plunger, crankshaft bearing, and bearing, and improves the service life of the plunger pump. (3) Improved production efficiency: Effectively reduced the number of unplanned shutdowns and maintenance time of plunger pumps due to water ingress, ensuring the continuous and stable operation of the steel rolling descaling process and reducing the impact of equipment failure on production line production; (4) Reduced maintenance costs: It reduces the frequency of parts replacement and maintenance labor costs, and avoids production losses caused by equipment failure. Practical application has verified that it has significantly reduced the overall operation and maintenance costs of plunger pumps. (5) High practicality: The device in this method is simple to manufacture and easy to install. It does not require large-scale modification of the plunger pump, has low operation difficulty, and is suitable for various types of horizontal plunger pumps for descaling in steel rolling. Attached Figure Description

[0013] Figure 1 This is a front view of the water-blocking cover of the present invention; Figure 2 This is a side view of the water-blocking cover of the present invention; Figure 3 This is a schematic diagram of the structure of the present invention; Figure 4 This is a schematic diagram of the packing sealing structure of the present invention; The markings in the diagram are as follows: 1. Water baffle; 2. Plunger; 3. Packing gland; 4. Packing box; 5. Support sleeve; 6. Packing assembly; 7. Stainless steel clamp; 8. Packing seal structure; 9. Crankcase; 10. Pump head; 11. Pump head inlet valve; 12. Pump head drain valve. Detailed Implementation

[0014] The invention will be further described below with reference to the accompanying drawings and examples.

[0015] See attached document Figure 1-4 A method for preventing water ingress into the crankcase of a horizontal plunger pump used for descaling in steel rolling mills is provided by installing a water baffle 1 and a packing seal structure 8 on the plunger 2 between the plunger pump crankcase 9 and the plunger pump head 10. The packing seal structure 8 includes a packing gland 3, a packing box 4, a support sleeve 5, and a packing assembly 6. The packing box 4 is fixed on the plunger pump head 10, and the plunger 2 inside the packing box 4 is provided with a packing gland 3 and alternately arranged support sleeves 5 and packing assemblies 6.

[0016] In this embodiment, refer to the appendix Figure 1-4 This method is applied to a horizontal plunger pump for descaling in medium plate rolling mills, with a plunger diameter of 150mm, a plunger center distance of 320mm, and a maximum plunger stroke of 280mm. The specific implementation steps are as follows: Step 1: Install the water barrier The water baffle 1 has a flared structure with the flared end facing the pump head. It can effectively block the water flow leaking from the plunger, realize the collection and discharge of the leaked water, and completely prevent the leaked water from entering the crankcase from a physical level. This avoids problems such as damage to parts and emulsification of lubricating oil caused by water ingress, ensures the stable and smooth operation of the plunger pump, and solves the loss of labor and spare parts costs caused by water ingress.

[0017] Design and installation requirements for water baffle 1: The installation position is 280mm+100mm from the crankshaft end plunger. Its inner ring diameter is 150mm and the outer ring diameter is 310mm. It is suitable for equipment parameters with a plunger diameter of 150mm and a plunger center distance of 320mm. It is made of 1mm stainless steel plate with a 20mm overlap at the interface. It is firmly fixed to the plunger 2 by stainless steel clamp 7 and forms dynamic protection with the reciprocating movement of the plunger.

[0018] Step 2: Install the packing assembly seal The stuffing box 4 is bolted to the plunger pump head 10. Inside the stuffing box 4, the plunger 2 is fitted with a stuffing gland 3, two sets of alternating support sleeves 5, and packing groups 6. The support sleeve 5 is a nylon sleeve or bakelite sleeve with an inner hole surface finish of grade 6 and a roughness of Ra1.6. It is precisely fitted with the outer surface of the plunger 2 at Φ90 (-0.036~-0.123) mm. Its inner hole size is Φ90 (0~0.087) mm. This ensures the fitting accuracy while avoiding the impact of excessive clearance on the support effect and the cause of plunger movement jamming due to insufficient clearance.

[0019] Packing group 6 consists of aramid graphite open rings, with the cuts of two adjacent aramid graphite open rings at 180° or 120° to each other.

[0020] By adding a support sleeve between the plunger packing and using an alternating arrangement of the support sleeve and packing, the support force of the plunger at the packing end is increased, the force distribution during the reciprocating motion of the plunger is optimized, the wear of the lower packing by the plunger's own weight is alleviated, the service life of the packing assembly is extended, and water leakage caused by packing wear is reduced, thus structurally reducing the risk of water ingress into the crankcase.

[0021] Step 3: Develop maintenance methods for the plunger parts of the horizontal plunger pump. This effectively extends the life of the plunger and packing, reduces the frequency of water leakage, and is also an effective way to prevent water from entering the crankcase.

[0022] A comprehensive maintenance method was developed for the plunger and packing components, standardizing aspects such as water quality improvement, component manufacturing processes, installation operations, and daily inspections. This improved the lubrication of the plunger and packing, reduced frictional losses, extended their service life, and decreased the frequency of leaks, thus further preventing crankcase water ingress from an operational perspective.

[0023] (1) Improve the quality of descaling water, increase the filter element precision of the self-cleaning filter in the descaling water supply system from 0.2mm to 0.15mm, and restore the timed cleaning function of the self-cleaning filter. Improved water quality can reduce friction between the plunger and the packing. (2) The surface roughness of the plunger is better than 0.8um, and there should be no defects such as cracks, dents, or scratches on the surface. The nitriding depth is greater than 0.5mm. This process can significantly improve the surface hardness and wear resistance. A good plunger surface can effectively reduce the friction coefficient between the plunger and the packing, extend the service life of the packing, and reduce the frequency of water leakage. (3) Clean the surface of the plunger before installation. Apply dry oil to the surface of the plunger before installation to improve the lubrication between the plunger and the packing. Check the surface of the plunger every day. If there are minor scratches, polish them with an oilstone and continue to use them. If the scratches are serious, replace the parts with new ones. (4) When connecting the plunger to the crankshaft end, center alignment and adjustment should be performed. The allowable deviation between the centerline of the stuffing box and the plunger should be ≤0.1mm to improve the centering accuracy and prevent accelerated wear of the stuffing caused by the deviation between the centerlines of the plunger and the stuffing. (5) The aramid graphite open ring is soaked in lubricating oil for more than 48 hours to allow the lubricating oil to penetrate into the packing and improve the lubrication between the plunger and the packing. (6) The packing gland 3 should not be tightened too much. Tighten it in place first, then turn it back 1 / 4 turn. When reinstalling old packing, the worn side should face upwards. The inner surface and sides of the packing should be smooth and flat. Do not use sharp objects such as screwdrivers to poke it in, as this will damage the sealing surface. Install the packing correctly and in place before installing the next packing. The cuts of the packing should be 180° or 120° to each other. Implementation effect

[0024] After the method of this embodiment was applied to the horizontal plunger pump for descaling in the medium plate mill, the problem of water ingress into the crankcase was completely solved, and faults such as lubricating oil emulsification, crankshaft bearing and bearing wear no longer occurred; the service life of the packing group was extended from the original 15 days to more than 60 days, and the replacement frequency of the plunger was reduced by 70%; the number of unplanned shutdowns of the plunger pump due to water leakage was 0, reducing equipment maintenance labor and spare parts costs by about 80,000 yuan per year, ensuring the continuous and stable operation of the steel rolling production line, with significant protective effect and economic benefits.

Claims

1. A method for preventing water ingress into the crankcase of a horizontal plunger pump used for descaling in steel rolling mills, characterized in that: A water baffle (1) and a packing seal structure (8) are respectively installed on the plunger (2) between the crankcase (9) and the pump head (10) of the plunger pump. The packing seal structure (8) includes a packing gland (3), a packing box (4), a support sleeve (5) and a packing group (6). The packing box (4) is fixed on the pump head (10) of the plunger pump. The packing gland (3) and the alternately arranged support sleeve (5) and packing group (6) are installed on the plunger (2) inside the packing box (4).

2. The method for preventing water ingress into the crankcase of a horizontal plunger pump used for descaling in steel rolling mills according to claim 1, characterized in that: The water baffle (1) is horn-shaped, with its horn opening facing the plunger pump head (10).

3. The method for preventing water ingress into the crankcase of a horizontal plunger pump used for descaling in steel rolling mills according to claim 2, characterized in that: The water shield (1) is fixed to the plunger (2) by a stainless steel clamp (7).

4. The method for preventing water ingress into the crankcase of a horizontal plunger pump used for descaling in steel rolling mills according to claim 1, characterized in that: The support sleeve (5) is a nylon sleeve or a bakelite sleeve, and the support sleeve (5) is precisely fitted with the outer surface of the plunger (2).

5. The method for preventing water ingress into the crankcase of a horizontal plunger pump used for descaling in steel rolling mills according to claim 4, characterized in that: The inner hole of the support sleeve (5) has a surface finish of grade 6 and a roughness of Ra1.

6.

6. The method for preventing water ingress into the crankcase of a horizontal plunger pump for descaling in steel rolling mills according to claim 5, characterized in that: The packing assembly (6) is an aramid graphite open ring, and the cuts of two adjacent aramid graphite open rings are 180° or 120° to each other.

7. The method for preventing water ingress into the crankcase of a horizontal plunger pump used for descaling in steel rolling mills according to claim 6, characterized in that: The stuffing box (4) is provided with a circular hole that mates with the plunger (2), the support sleeve (5) and the packing assembly (6).

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