Hot-rolled 1580 Coiler
The mechanical structure and expansion and contraction principle of the reel of the 1580 hot rolling coiler, the main reasons for the core pulling of the reel are mainly analyzed, and the improvement and preventive measures to effectively avoid the core pulling are discussed .
【Key words】coiler; mechanical structure; expansion and contraction; core pulling
1580 hot rolling is a production line integrating a number of advanced technologies and advanced new equipment. It has many types of rolling products, high rolling precision and high degree of automation.
The 1580 hot rolling coiling area is used for coiling and forming strips of different specifications. It is first cooled by the strip cooling system, and then transported to the coiler by the laminar flow roller table for final coiling; then, the formed steel coil is transported to the coil bundling station by the unloading trolley located under the coiler, and finally , the bundled steel coils are transported to the transport chain by means of a coil trolley. However, recently, during the unloading process of coiling, the core pulling phenomenon of the reel often occurs, causing the formed steel coil to be stuck on the reel and cannot be unloaded, which seriously delays the production rhythm and has a certain impact on the shape of the steel coil.
- The mechanical structure and expansion and contraction principle of the reel of the coiler
1580 hot rolling adopts cantilever type hydraulic expansion and contraction reel, mainly composed of fan-shaped plate, pyramid sleeve , plate pin and mandrel and other reel components, relying on the main motor to drive through gear distribution box, gear adapter and 2- stage gear reducer .
The mechanical structure of the reel is a four-wedge type, and the expansion and contraction are completed by a rotary hydraulic cylinder. The reel sector plate is connected to the mandrel through the plate pin, and can slide on the quadrangular pyramid sleeve through the mandrel. The principle is that the rotary hydraulic cylinder drives the fan-shaped plate to move in the axial direction through the mandrel. When the mandrel drives the fan-shaped plate to move to the transmission side, the relative position between the reel fan-shaped plate and the square pyramid sleeve slides in the direction of high taper, and the reel fan-shaped The position height of the plate will increase in the radial direction, and the reel will expand with the increase of the position height of the fan-shaped plate in the radial direction; The relative position between them slides in the direction of low taper, the position height of the fan-shaped plate of the reel will decrease in the radial direction, and the reel will shrink as the position height of the fan-shaped plate decreases in the radial direction, thus realizing the reel and fan-shaped plate. Shrinkage control.
When the reel expands and shrinks, the action is stable, the structure is compact, and the service life of the parts is long; but due to the frequent expansion and contraction of the reel, the contact surface between the mandrel and the plate pin wears quickly, and a gap will be generated when the wear reaches a certain amount, causing the reel If the expansion and contraction are not in place, in severe cases, the forming steel coil will be stuck on the reel, causing the failure of the core pulling of the reel.
- Core Pulling Cause Analysis
During the unloading process of coiling, the unloading trolley rises until it withstands the formed steel coil, and then sends out an unloading command. The expansion and contraction cylinder pushes the mandrel to drive the fan-shaped plate to slide on the pyramid sleeve to the head of the reel, and the reel The shrinkage makes the inner diameter of the steel coil larger than the diameter of the reel, and the steel coil immediately falls on the roller of the unloading trolley, and then the unloading trolley supports the steel coil and moves to the outside of the reel, but often in the process of removing the steel coil, sometimes the steel coil is found The coil is stuck on the reel for some reason, so that the trolley cannot unload it from the reel smoothly, which leads to the core pulling failure of the reel, affecting the shape of the steel coil and the production rhythm.
After on-site investigation and analysis, it is concluded that the main causes of common reel core-pulling failures are as follows :
- Roll expansion and contraction are not in place
During the coiling process, due to the frequent expansion and contraction of the reel, the mandrel 1 pulls back and forth in the axial direction to hit the plate pin 4 , causing wear on the contact surface of the plate pin 4 , and a gap e will be generated when the wear reaches a certain amount . (As shown in Figure 1 below )
When the reel shrinks, the mandrel 1 pushes the plate pin 4 under the action of the hydraulic cylinder to drive the fan-shaped plate 3 to move towards the head of the reel. Because of the gap e between the plate pin 4 and the mandrel 1 contact surface , the fan-shaped plate 3 cannot Slide to the taper bottom of the pyramid sleeve 2 , and the axial distance from the bottom of the pyramid sleeve is also
is e , so that the height of the sector plate 3 in the radial direction is higher than the distance h when it is normally contracted , so that the reel does not shrink in place, so that the inner ring of the steel coil is in contact with the surface of the reel when it is pulled out, and it will be stuck on the reel in severe cases surface, causing core-pulling failure.
- Internal leakage of hydraulic circuit
During the coil unloading process, the coil unloading trolley maintains a certain pressure until it touches the surface of the steel coil. After the operation is confirmed, the coil unloading command is issued immediately. The coil shrinks so that the steel coil falls completely on the trolley, and the solenoid valve 1/26 is in the middle position . The oil cavity of the trolley jack lifting cylinder is cut off by four cartridge valves to form a closed space, and the corresponding pressure in the oil cylinder cavity will change to balance the load of steel coils of different specifications.
If the steel coil load is large, the pressure in the jacking cylinder is lower than the steel coil load, and the pressure in the rodless cavity will rise sharply to balance the steel coil load when the coil is unloaded. Leakage in the circuit increases, which reduces the volume of the rodless cavity, that is, the trolley will lower the steel coil to a certain height. If the descending height is too large, the inner ring of the steel coil will contact the surface of the friction reel, resulting in a core-pulling failure.
Calculation of the lift of the small car roof:
The piston diameter of the oil cylinder is: 200mm ; the system pressure is 200kg/cm 2 ; the jacking pressure is set to 85kg/cm 2 ; therefore, the jacking cylinder pressure is:
2
Fi=Pi x S] =85 x 0.25 x n x 20 =26690kg=26.69t
Calculation of the descending height of the trolley:
weight of the largest steel coil for coiling is 26t ;
Cylinder stroke: 1710mm
P 1 V 1 = P 2 V 2 ； ^ P i S i h i = P 2 S 2 h 2 ； ^ F 1 h 1= F 2 h 2
h 2 =F 1 h 1 /F 2 =26.69 x 1710/(26+1)=1690.4mm
Namely: The descending height of the trolley is: △ h=h 1 -h 2 =1710-1690.4=19.6mm
The expansion diameter of the reel is: 762mm ; the shrinkage diameter of the reel is: 730mm ;
Drop height △ h>(762-730)/2=16mm
Therefore, when the pressure in the oil cylinder changes sharply, the leakage in the hydraulic circuit will easily increase, resulting in the reduction of the volume in the rodless cavity of the oil cylinder, which will cause the core pull of the reel.
- Improvement and preventive measures
3.1 Adjust the stroke of expansion and contraction cylinder
The core pulling failure caused by the wear of the plate pin can be improved by adjusting the moving stroke of the expansion and contraction cylinder. Adjust the screen cap of the oil cylinder as shown in the figure below to make the piston rod of the oil cylinder expand and contract (continued to page 829 )
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