RU1788412C - Method of controlling hydraulic system of vertical motion mechanism of walking beams of heating furnaces - Google Patents

Description

The purpose of the invention is to increase the reliability of the hydraulic system for lifting walking beams of heating furnaces.

This goal is achieved in that in the method of controlling the hydraulic system of the mechanism of vertical movement of walking beams, including pumping working fluid from the pump through a non-return valve and a hydraulic lock into the hydraulic cylinder for raising the beams when they are raised, opening the hydraulic lock at the moment of lowering the beams, before lowering the beams the pumping fluid is pumped into the main manifold through a check valve with a discharge pressure of 0.9-1.1 pressure under the ram of the lift cylinder.

In FIG. 1 shows a hydraulic system for a vertical beam movement mechanism; in FIG. 2 and 3 are pressure oscillograms of the hydraulic system when lowering the beams for the prototype and the proposed method, respectively.

The hydraulic system of the mechanism of vertical movement of walking beams consists of a pump 1, a check valve 2, a hydraulic lock 3 with a distributor for its control 4, an actuating (lifting) hydraulic cylinder 5, distributors 6, flow controllers 7. The entire control apparatus is connected by a central manifold and pipelines , On the rod of the cylinder 5 are movable lifting beams 8, on which the workpieces 9 lie.

The hydraulic system works as follows,

The working fluid from the pump 1 through the check valve 2 and the hydraulic lock 3 is fed under the plunger of the hydraulic cylinder 5, the plunger raises the beams 8 with the blanks lying on them 9. After raising the beams, the hydraulic lock 3 is closed by the distributor 4, pump 1 is turned off. The beams are supported by the working fluid locked in the hydraulic cylinder 5. Then the beams are horizontally moved, after which the beams must be lowered. For this opens-. from the hydraulic lock 3 and the working fluid is drained through distributors 6 and flow controllers 7 into the tank.

At the moment of opening the hydraulic lock 3, the mass of fluid in the hydraulic cylinder 5 is locked, under the influence of the weight of the plungers, beams and billets, is drained into the main and drain manifold. There is a direct water hammer on the hydraulic lock 3, check valve 2, valves 6 and flow controllers 7, which leads to a decrease in the reliability of the mechanism as a whole.

Simultaneously with the horizontal movement of the beams, pump 1 is turned on and pumps the working fluid into the main manifold of the hydraulic lift system, the discharge pressure being equal to (0.9-1.1) the pressure under the ram of the lifting hydraulic cylinder 5

P2 (0.9-1.1) Pi.

By injecting the working fluid, the pump thereby creates a cushioning pad under the hydraulic lock 3 and, when the hydraulic lock 3 is opened at the moment of lowering the beams, the entire mass of liquid from under the plunger falls onto this pad, the direct water hammer and pressure fluctuations in the hydraulic system disappear.

At a discharge pressure value of 0.9Pi, there is not a complete exclusion of water hammer in the system and incomplete disappearance of pressure fluctuations. At a value of PZ 1.1 Pi, a situation arises when lowering the beams is difficult due to the large support of the cylinder plunger.

The oscillogram of the pressure in the hydraulic system at the moment of lowering the beams (for the prototype) is shown in Fig. 2. As can be seen from the presented oscillogram (Fig. 2), the pressure Pi (under the plunger of cylinder 5) at the moment of opening the hydraulic lock 3 increased from 10.5 MPa to 18, 0 MPa for a very short period of time, approximately (T 0.2-0.3 s), direct water hammer - increase in pressure in the system for a short period of time. The pressure Ra (in the central manifold) rises from 3 MPa to 20.5 MPa in a time of 0.3-0.4 s, and there is also a water hammer. From the same waveform, the pressure in the manifold and under the ram of the lift cylinder fluctuates. .

A pressure waveform in a hydraulic system with a new control method is shown in FIG. 3. The latter shows how pressure peaks are cut off and vibrations disappear in the main manifold and under the plunger of hydraulic cylinder 5.

The exclusion of water hammer and pressure fluctuations in the system will improve the reliability of the system by 30-40%,

Claims (1)

The claims A method for controlling the hydraulic system of the mechanism for vertical movement of walking beams of heating furnaces, including pumping working fluid from a pump through a check valve and a hydraulic lock into the hydraulic cylinder for raising the beams when they are raised, opening the hydraulic lock at the moment of lowering the beams, characterized in that, in order to increase reliability due to to eliminate hydraulic shocks in the system, before lowering the beams, the working fluid is pumped into the main manifold by a pump through a non-return valve with a discharge pressure of 0.9-1.1 and under the ram of the lift cylinder. Whose L 0m / jp. 0.3-0.4 s 30 # p. fy & Ј0 / v6 / # 0 # Ј / e 9 / ge # luyu ) / LG0 MY70G Zt / fyo30M # C ( FIG. g 30wnp0rtcr # t / ffr t / 0p0s & / Mct 3 & xp.