Created on：2021-08-05 10:04

# Maintenance of roller_ Problems and analysis of balance hydraulic control circuit

Maintenance of roller_ Problems and analysis of balance hydraulic control circuit

轧辊平衡装置是用来平衡轧机的轧辊及轴承座等的重力，以消除由于轧辊辊径和轴承衬间、轴承座和压下螺钉头部间、压下螺钉和压下螺母的螺纹间存在间隙而造成轧件咬人时对轧辊的冲击。平衡装置有弹簧平衡、重锤式平衡、液压平衡等形式。液压平衡装置因具有结构紧凑、动作灵活、工作平稳、操作和拆卸方便等特点，而得到了广泛的应用。
The roll balancing device is used to balance the gravity of the roll and the bearing pedestal of the rolling mill, so as to eliminate the impact on the roll when the rolled piece bites due to the gap between the roll diameter and the bearing liner, between the bearing pedestal and the screw head, and between the screw thread of the screw and the nut. There are spring balance, weight balance, hydraulic balance and so on. Hydraulic balance device has been widely used because of its compact structure, flexible action, stable work, convenient operation and disassembly.

(1)常规轧辊平衡回路分析
(1) Analysis of conventional roller balance circuit

某钢厂一条450mm热轧窄带钢生产线的轧机主要由立辊轧机E1、E2，二辊轧机F1、F2，四辊轧机F3、F4、F5、F6组成。其中二辊轧机及立辊轧机的轧辊平衡、四辊轧机的支撑辊平衡系统均采用了图I所示的控制回路。轧辊平衡时，电磁铁DT1、DT2均不带电，系统压力油经7、6、5、单向节流阀3的节流阀通向轧辊平衡缸的无杆腔，产生一个向上的推力F1。同时，系统背压经电磁换向阀8加在平衡缸的有杆腔，产生一个向下的力F2，则施加到轧辊上的平衡力F=F1-F2；当平衡缸的活塞杆在轧机压下系统的作用下退回时，平衡缸无杆腔的液压油经溢流阀2流回油箱；当需要平衡缸活塞杆退回时，电磁铁DT1、DT2同时带电，系统压力油经电磁换向阀8加在平衡缸的有杆腔，同时平衡缸无杆腔的液压油经节流阀4、电磁换向阀6回油箱，完成平衡缸活塞杆的回退动作。
The rolling mill of a 450mm hot strip production line in a steel plant is mainly composed of vertical roll mill E1 and E2, two high mill F1 and F2, four high mill F3, F4, F5 and F6. The control loops shown in Fig. I are used in the roll balance system of two high mill and vertical mill, and the backup roll balance system of four high mill. When the roll is balanced, the electromagnets dt1 and DT2 are not charged, and the system pressure oil flows through the throttle valve of 7, 6, 5 and one-way throttle valve 3 to the rodless cavity of the roll balance cylinder, generating an upward thrust F1. At the same time, the back pressure of the system is applied to the rod cavity of the balance cylinder through the electromagnetic directional valve 8, and a downward force F2 is generated, then the balance force applied to the roll f = F1-F2; When the piston rod of the balance cylinder returns under the action of the rolling mill screwdown system, the hydraulic oil in the rod free cavity of the balance cylinder flows back to the oil tank through the relief valve 2; When the piston rod of the balance cylinder needs to be returned, the electromagnets dt1 and DT2 are charged at the same time, the system pressure oil is added to the rod cavity of the balance cylinder through the electromagnetic directional valve 8, and the hydraulic oil without the rod cavity of the balance cylinder returns to the oil tank through the throttle valve 4 and the electromagnetic directional valve 6 to complete the return action of the piston rod of the balance cylinder.

该平衡控制回路在轧辊平衡时不需要电磁铁带电，避免了因长期带电而烧毁电磁铁线圈的现象，所构成的轧辊平衡系统工作平稳、可靠，基本满足了生产的需要，但在换辊时该回路存在一些问题。
The balance control circuit does not need the electromagnet to be electrified when the roll is balanced, which avoids the phenomenon of burning the electromagnet coil due to long-term electrification. The roll balance system composed of this circuit works stably and reliably, and basically meets the needs of production. However, there are some problems in the circuit when changing rolls.

(2)原回路存在的问题
(2) Problems in the original circuit

现代轧机一般都要求具有快速换辊功能。该轧机的轧辊平衡装置采用单液压缸形式，上轧辊的装配体通过平衡吊钩吊挂在一平衡粱上，平衡梁通过一个平衡缸向上拉，紧紧压靠在压下系统上。
Modern rolling mills generally require quick roll change. The roll balancing device of the mill adopts the form of single hydraulic cylinder. The assembly of the upper roll is hung on a balance beam through a balance hook. The balance beam is pulled up through a balance cylinder and tightly pressed against the screwdown system.

卸辊的操作顺序如下：
The operation sequence of roll unloading is as follows:

①将电动压下螺钉回退到换辊位置，以使上轧辊轴承座与下轧辊轴承座之间的凸凹槽分离；
① The electric screwdown screw is retracted to the roll changing position to separate the convex groove between the upper roll bearing seat and the lower roll bearing seat;

②吊挂缸动作，将压下缸吊起，此时由于轧辊平衡装置的作用，上轧辊上升到换辊位置；
② The hanging cylinder acts to lift the screwdown cylinder. At this time, due to the function of the roll balancing device, the upper roll rises to the roll changing position;

③下轧辊由换辊缸通过换辊拖板向操作侧移动一距离，使下轧辊轴承座的凸块脱离上轧辊轴承座的凹槽；
③ The lower roll moves a distance from the roll changing cylinder to the operation side through the roll changing carriage to make the convex block of the lower roll bearing seat separate from the groove of the upper roll bearing seat;

④轧辊平衡缸由平衡力控制状态变为位置控制状态，将上轧辊及轴承座落下，使上轧辊轴承座的下平面落在下轧辊轴承座的凸块上，同时使平衡吊勾支撑面与轴承座吊耳脱离，保持大约10mm间隙，并锁定位置}
④ The roll balance cylinder changes from the balance force control state to the position control state. The upper roll and the bearing seat are set down to make the lower plane of the upper roll bearing seat fall on the convex block of the lower roll bearing seat. At the same time, the supporting surface of the balance hook is separated from the lug of the bearing seat to maintain a gap of about 10 mm and lock the position}

⑤辊系定位于待换位置后，轴头定位升降缸动作，带动轴头卡紧装置下行到换辊位置，对准接轴轴头；
⑤ After the roller system is positioned at the position to be changed, the shaft head positioning lifting cylinder acts to drive the shaft head clamping device down to the roll changing position and align with the shaft head;

⑥轴头抱紧缸动作，推动卡块转动，同时卡紧上下轧辊接轴的轴头；
⑥ The shaft head hugs the cylinder to push the block to rotate, and at the same time, the shaft heads of the upper and lower rollers are clamped;

⑦换辊缸动作，换辊钩与换辊拖板的钩头连接，换辊缸有杆腔充油，换辊拖板带动辊系经滑轨从牌坊内抽出。
⑦ The roll changing cylinder acts, the roll changing hook is connected with the hook head of the roll changing carriage, the rod cavity of the roll changing cylinder is filled with oil, and the roll system is pulled out from the archway by the slide rail driven by the roll changing carriage.

新辊的安装按照上述相反的顺序操作。
The installation of the new roll is in the reverse order.

由于上述轧辊平衡回路所控制的平衡缸没有中间位置，不能满足换辊操作顺序中的步骤④的要求，所以需对其进行改进。
Because the balance cylinder controlled by the roll balance circuit has no middle position, it can not meet the requirements of step 4 in the roll change operation sequence, so it needs to be improved.
Because the balance cylinder controlled by the roll balance circuit has no middle position, it can not meet the requirements of step 4 in the roll change operation sequence, so it needs to be improved.

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