Installation of hydraulic equipment for graphic analysis
1. installation of hydraulic pressure pipe
(1) the basic conditions for the selection of hydraulic tubing must have sufficient strength, the inner wall of the pipe must be smooth, clean, no sand, no rust, no oxidation with defects such as on long-term storage tube, consider the impact of corrosion, before use must be washed after pickling, to check whether the resistance (the poor quality of the main pipe as the thickness of the pipe wall is not uniform or wire layer tension and pull the fabric tight bearing capacity reduce).
(2) the connection and installation of piping system for ocean piping with stainless steel welding result, often by hydrogen arc welding process with hydrogen protection. When welding, the ends of both sides of the welding joint are sealed, and hydrogen is filled in the nozzle, and the hydrogen arc is applied to the butt welding port to fill the hand arc. Without welding process requirements, the weld area shall be cut open, and the weld shall be porous, cavernous and extremely irregular. The welding seam in this state can not guarantee the welding strength at all, and leakage is easy to occur. Welding current should not be too large, otherwise it will cause tumor dripping, affecting the flow of liquid in the pipeline, resulting in unnecessary pressure loss.
System flange welding is difficult in pipe production. If the welding process is wrong, it is easy to flange deformation bulge. When the welding temperature is too low, the temperature difference between the welding zone and the non welding zone and the welding layer causes the uneven stress distribution in the flange wall, resulting in poor welding quality. Take the corresponding measures (such as induction heating, etc.) to ensure that the temperature difference between the welding area and the non welding zone is not great, and the temperature difference between the welding layers is not more than 200 degrees. It can solve the problem of flange deformation effectively.
It is a common method to inspect the quality of welded joints by flaw detection. Common methods of flaw detection include X- ray flaw detection and ultrasonic flaw detection, but they have some limitations. For example, X- ray inspection, for the wall thickness greater than 18mm welding hole can not be accurately determined. There are also similar problems in ultrasonic inspection, and ultrasonic flaw detection can not analyze the defects of butt welds. The combination of two inspection methods will be beneficial to check out the unqualified welding joint.
During installation, when the tubing needs to be cut off, the vertical direction of the cross section and the axis is 90 degrees + 1/2 degrees.
At the same time, the sharp edges must be blunt and remove iron filings. If the installation of pipelines, pipe the maximum allowable bending radius of elbow was 10%, more than three times the pipe diameter, to consider the shortest pipeline, less bend, pipe support distance is not too large, the support may have loose, and the minimum bending radius of maximum spacing of the support tube allowed as shown in table 10-1.
The highest point of the line must be provided with an exhaust device to release air in the pipe for start-up.
Installation of oil suction pipe must not leak, so as not to attract people's air, causing crawling; suction pipe resistance should not be too high, otherwise it will cause cavitation.
The oil return pipe should be extended below the oil level of the tank, so as to prevent the splash from causing bubbles. The oil return pipe used as the overflow valve must be communicated with the pump population through the tank. Otherwise, the oil temperature will rise rapidly.
(3) when the hose is installed in a rubber tube as a hydraulic tube, in order to guarantee the normal operation of the high pressure hose and prolong the service life, the following principles should be observed when installing the high-pressure hose:
1) avoid sharp bends. The bending radius after installation of the hose shall be no less than 8-10 times of the outer diameter of the hose. The root of the joint at both ends of the hose shall not be bent, and a certain straight line shall be retained, and its length shall be no less than 6 times of the outer diameter of the hose. To avoid sharp bending, it is possible to bend the spring outside the hose or support the steel strip so that it can be bent smoothly.
2) there is no distortion allowed. In the process of tightening the ends of the hose, this problem is easy to occur. It will change the braiding angle of the wire braid, make the hose uneven and bear the pressure drop. To avoid distortion, a straight line parallel to the centerline of the hose can be drawn by chalk on the hose before assembly, so as to check whether the hose is twisted after installation.
3) in the length of the direction, the kernel should have a certain amount of relaxation, can not make it in a tense state, in the replacement of new hoses, we should pay attention to this point. Because of the high pressure oil hose factory, full length contraction 3%~4%, surface hydraulic cylinder in the process of lifting a certain amplitude of oscillation. If the hose length is not enough, the two hoses can be lengthened by connecting through the transition joint.
4) the contact and friction between the hose and the machine or the driver's cabin shall be avoided as much as possible so as to prevent abrasion of the outer layer and the wire braid. In cases where mechanical friction may occur with the outside world, a canvas belt or rubber hose may be wrapped to protect it.
5) hydraulic traction tractors (or dump trailers) shall be fitted with safety fittings between hose and tractor to prevent the hose from breaking and leaking due to the decoupling of the farm tools.
2. installation of hydraulic components
(1) outlined in the installation of hydraulic components, components must be pressure and sealing test. Hydraulic pump and its transmission must have higher concentricity, even flexible coupling should be concentric, must ensure concentricity below O.1mm, tilt angle is not greater than l degrees. A variety of control valves should pay attention to the oil inlet and back to the specific location of the oil can not be reversed.
With the valve flange mounting screws, not too tight, should be determined according to the specific requirements of the product, because sometimes too tight but will cause bad sealing or single pressing interface; hydraulic cylinder installation should consider the effect of thermal expansion in large stroke and high temperature, must ensure that the end of the cylinder at the same time, floating sealing ring the hydraulic cylinder is not installed too, especially the U ring, so as not to cause too much resistance.
(2) the installation of hydraulic pump and hydraulic motor hydraulic pump and hydraulic motor are required such installation: pump and motor shaft end shall not generally will not bear radial force, belt wheel, gear parts directly installed in the pump and motor shaft. Failure to comply with the above requirements will result in failures and economic losses. For example, a German ABG423 asphalt paver, screed lifting mechanism of the hydraulic pump is connected by gear drive, as shown in figure 10-1.
This kind of hydraulic pump is a gear pump, and the paver often appears after the use of a period of time, the ironing board lifting speed is slow, and even can not lift the fault. The reason for this, almost without exception, is that the hydraulic pump leaks too much. By dismantling the hydraulic pump can be found, sweeping serious, resulting in relief: the cause of sweeping is due to bending deformation wear and shaft bearing, dismantling can also be found that the pump bearings are generally not excess wear, the bending deflection of a shaft that is mainly caused by the sweep chamber, and the pump is not installed right is the fundamental cause of this problem, as shown in figure 10-2.
The gear pump is connected by gear transmission, gear transmission will produce radial force is the cantilever shaft radial force in gear pump, cause the additional deflection, resulting in low pressure, sweeping, not to mention the fault of the screed.
The driving motor of a YE-160 type conveyor is shown in Figure 10-3. The driving sprocket is driven by a hydraulic motor, and the driven sprocket drives the belt roller.
The motor often leaks, and less than 1 months after the sealing ring is replaced. Because the car is at the airport, especially high institutions on the leakage requirements, all vehicles prohibited near the plane leakage, so the maintenance personnel only constantly replace the seal, causing great waste of manpower, money and time.
The hydraulic motor drives the belt pulley by chain drive, and the radial force is generated by the chain drive, and the oil seal is deformed after the radial force, leading to oil leakage
As shown in Fig. 10-4, the hydraulic motor of the unloader is no longer subjected to radial force, and the oil leakage problem can be solved.
(3) tank and filter installation in order to ensure that the suction and the cleanliness of hydraulic oil hydraulic pump, generally require pump installation as close to the tank, and the tank shall be located above the hydraulic pump, and a filter is arranged at the oil line. Some of the equipment's failures are due to the neglect of the problem. For example, a hydraulic equipment often walk weakness, climbing ability is not strong, and even can not walk. Inability to walk or walk at all. The installation of the tank is close to the hydraulic pump, the position is higher than the pump, and the installation of the filter, but why is there a problem?
The hydraulic system is a closed system, the main pump oil is supplied by the oil pump. The amount of oil pump not only supplement the main discharge of oil and oil due to losses, but also will be the main oil in the oil replacement out for cooling, to prevent the oil temperature is too high, while providing a pressure source variable mechanism: as can be seen from figure 10-5, the hydraulic oil pump up through the siphon pipes. Then through the filter before reaching the pump. Siphon will produce vacuum, through the filter pressure loss, the two add together, fill the oil pump suction port of the vacuum is very large, which lead to the lack of oil absorption pump, or even broken oil. Once the oil break occurs, the variable control mechanism can not work properly, the hot oil of the main oil circuit can not be fully replaced, and the oil temperature is increased.
Demolition of the hydraulic pump, found that the main pump has oil, carbonized sediment, which shows the hydraulic pump had a high oil temperature conditions. If this fault lasts for a long time, the mountain in the oil temperature is too high, will not only make the hydraulic pump with oil and other early wear, and even make the hydraulic pump lose their ability to work. But because the whole oil temperature is not high, even below the normal value, only in closed oil circuit in the circulation of oil temperature is high, so that will cause oil temperature is not high illusion. Because generally, the oil temperature is measured in the oil tank temperature, which will easily lead to difficulties in diagnosis and miscarriage of justice, should be paid enough attention. Therefore, pay attention to changing the filter frequently to ensure that the inlet pressure and vacuum meet the application requirements.
