The Distribution of Pipeline in Hydraulic System of Construction Machinery
Gravity, rotate around 4 o'clock, so as to relax the brake lever, and the brake lever will rapidly reach the pulley part under the action of the spring and insert into the abdominal hole of the pulley. The pulley is braked, and the lifting steel rope can no longer rotate with the pulley. Pulling the luffing car, it played a safety role.
The comparison scheme and scheme 2 can be seen that both of these schemes can play the role of safety protection of the brake car when the luffing wire rope is broken. The program uses the boom horizontal abdominal rod to brake the trolley. The impact between the brake rod and the web rod is severe and the impact is large, but the brake is rapid. The scheme 2 utilizes the hoisting mechanism steel wire rope to brake. Due to the flexibility of the wire rope itself, the braking speed is particularly slow when the no-load vehicle runs at a high speed.
Finally, it is worth noting that despite the installation of anti-rope protection devices on the luffing cart, it is still necessary to install on both ends of the boom. Limiting device to prevent car out of bounds and break rope protection device failure.
In the recent years, China imported many construction machinery that were produced in other countries, especially many excavators imported from Russia. Over time, these machines The reliability is gradually declining, especially the hydraulic system's failure rate is getting higher and higher. In order to get rid of the predicament, many units began to use existing domestic components to modify the original hydraulic system. We found that many tuners only pay attention to the selection and modification of large components, but they ignore the fitting of hydraulic lines. Let's talk about our experience on how to configure the hydraulic system pipeline.
1 Reasonable Selection of Hydraulic Tubing 1.1 Internal Diameter of Tubing Tubing The internal diameter of the tubing is mainly determined by the requirement of pipeline flow. When the inner diameter is too small, the pressure loss increases when the hydraulic oil flows through the pipe, and the oil temperature increases. If the inner diameter is too large, bending processing is not easy, the piping layout space is increased, installation and arrangement are difficult, and the weight of the machine is increased. The choice of tubing inner diameter can be calculated according to the following formula Q flow rate through the tubing, claw, 1 v oil flow speed, 8 its flow speed 1 value range is 26,15, when the system pressure high flow, it takes a large value, otherwise Take a small value.
The calculated inner diameter of the tubing should also be selected according to the specifications of the steel tube.
1.2 Thickness of the wall of the metal pipe The thickness of the pipe wall should meet the strength requirements. The thickness of the metal pipe wall can meet the strength requirements of the hydraulic system. For safety, the maximum pressure of the oil in the P pipe can be verified by the following formula. The allowable tensile stress is MPa. For the copper pipe, it is desirable for the steel pipe. 7,7 7 Desirable 714. The tensile strength of the steel pipe is different depending on the materials used. If the concrete material of the pipe cannot be determined, it can be calculated as =600 river.
1.3 Determination of Working Pressure of Rubber Hose After selecting its inner diameter, the rubber hose should also determine its proper working pressure.
The rubber hose standard generally states that its breaking pressure is a multiple of the rated working pressure. After determining the working pressure of the system, the actual required working pressure shall be determined according to the working conditions of the rubber tube and the hose subjected to the static pressure shall be selected. The pressure may be selected to be the destructive pressure of 12,13; the hose subjected to the impact pressure shall have a working pressure. The 1314 selected to break the pressure; the hose subjected to the impact load and frequent bending action, the pressure of 1 should be selected as the 14 stone that breaks the pressure.
When the damage pressure is not easy to determine, the working pressure of the rubber hose can be determined according to 2, 3 times the working pressure of the system. Determine the rubber hose specifications, mainly to see the number of layers inside the hose.
Construction machinery, 20007 selection of tubing should also consider the smooth and clean inner wall without sand, no rust, no scale, etc., in order to prevent leakage of hydraulic systems, pollution and pressure loss.
2, Washing and processing hydraulic pipe fittings Cleaning hydraulic fittings After the hydraulic pipe fittings are purchased, they are generally cleaned. For relatively new net fittings, only oil can be washed. For more oil, internal corrosion of the pipe, especially the original mechanical pipe fittings, in the progress of 1; before pickling, thoroughly, wash and wash the inner wall, but also to check whether the durability after washing.
When cutting metal fittings of cutting parts, they should be cut with a cutting machine or pipe cutter, and the cuts should be smooth and smooth when cutting. The perpendicularity of the pipe cutting section and pipe axis direction should be 90±0.5, and the sharp edges of the pipe should be inverted and iron scrap should be removed. The end 4 of the oil inlet pipe and the suction pipe in the crucible box should be cut into oblique mouths to reduce the influence of impurities in the oil crucible on the system.
The ellipticity of the bending process of metal pipe fittings should be less than 10. For this reason, when the pipe diameter is small, the pipe can be bent manually by using a manual method. If the pipe diameter is large, the pipe bender is used to bend the pipe. To ensure less irregular deformation, the tube bends can be heat annealed before bending. The bend radius at the elbow should be more than the diameter of the larger tube.
The reaming of the metal pipe fittings shall be carried out with a reamer. To ensure that the reaming is even and smooth, the pipe head may be heated and annealed before reaming.
3 Prerequisites for installing hydraulic pipe fittings to ensure system function The installation of piping should minimize the distance of the entire pipeline, and the number of turns should be as small as possible. The same pipeline shall be installed as horizontally as possible. The exhaust fitting shall be installed at the highest position of the non-horizontal installation path so that the air in the pipeline can be excluded when necessary. When the rubber hose is installed, sharp turn should be avoided and the corner should be turned. Half of the body should be the diameter of the body. Do not bend near the joints of the hoses. The length of the hose joints to the bends should be twice the diameter of the elbow, and the installation of the hoses should not be twisted.
The installation of the suction pipe in the oil tank should be installed as horizontally as possible, and the oblique mouth of the pipe should be oriented horizontally to reduce the inhalation of impurities in the tank. The suction pipe must not leak, so as not to inhale air.
The installation of the oil return pipe shall be such that the nozzle of the pipe is inserted into the oil surface to prevent the oil from flying. At the same time, the nozzle of the return pipe in the tank should not be too close to the bottom of the tank to prevent the return flow from flushing the impurities at the bottom of the tank.
The installation of the entire pipeline should be carried out in two steps. The first trial assembly is performed. During the trial assembly process, the pipelines and their joints are installed in their proper locations, and where necessary, they can be fixed by spot welding. The first step is to confirm that the installation position of the fittings is reasonable and without any interference, remove all the fittings, thoroughly clean, and then repair the faults of the 5,3 type Lingshu Weipan starter Xuzhou Heavy Machinery Factory Chen Guoping China University of Mining and Technology Wang Meiji At the crane commissioning site, I encountered the fault of the starter's idling after the start-up key switch was turned on by the 503-type Japanese-foot crane crane. Through the power switch, start the battery relay, then the whole car has electricity and then start the key switch to the start position, start the relay normally open contact is closed, the current path through the maintenance of the winding 1 back to the negative, the other way through the suction When the starter motor field winding and the armature winding return to the negative pole, the two windings of the electromagnetic switch simultaneously pass the current, and the strong magnetic field generated by the two windings attracts the iron core downward and drives the driving lever to rotate, so that the starter gear and the flywheel tooth Ring machine, 20007 into the meshing state; iron core continues to move downward, pushing the two contact sheets of the movable contact piece to close. Began work machine, this time around the beginning of the suction cyanosis and ends due to the main contacts are closed off, the suction force of the electromagnetic switch is maintained only by holding the winding. After the engine is started, release the key to sweat
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