Although the hydraulic system of the bending machine is relatively high in reliability, the system is complicated and has many components. Once the fault occurs, it is difficult to detect or process the eyebrows. Especially in large bending machines, the complexity of its hydraulic system far exceeds people's imagination. Therefore, the maintenance of such equipment is a problem that plagues maintenance workers. Taking a certain type of hydraulic bending machine as an example, the author exemplifies some maintenance techniques based on the analysis of the causes of common faulty machines.
This study takes the typical hydraulic bending machine WC67Y-100T/3200 produced by Shanghai Punching and Cutting Machine Tool Factory as an example, as shown in Figure 1. This type of hydraulic bending machine has not been put into the market for a long time. It has advanced design, flexible operation and powerful functions. It has been widely used in the automotive, shipbuilding, metal rolling and other industries to show a good application effect. At the same time, its high degree of automation and large upgradeable space are very typical hydraulic bending machines. However, in the long-term use process, the pool often has some faults, such as the slider is seriously insufficient when the system is under pressure, and the slider is extremely slow when returning.
Figure 1——WC67Y-100T/3200 press brake machine
This type of hydraulic bending machine is mainly composed of a quantitative piston pump, a slider, a valve and an electromagnet, and is a typical hydraulic structure. Its workflow is fast downwind, slow slider approach, pressurization, pressure holding, pressure relief, and return. The up and down movement of the slider is the basis for hydraulic control, and at the same time, because its most sporty pool is the most prone to fault, this is also confirmed in actual operation. In addition to this, the quantitative piston pump in the hydraulic system is a relatively delicate equipment pool and is prone to failure. Therefore, the two subsystems should be closely watched during the process of repairing the hydraulic bending machine.
The most common fault of the hydraulic control system is that the slider pressing force is insufficient and the return speed is slow when the hydraulic cylinder is under pressure. This failure not only causes the hydraulic system's handling performance to be greatly reduced, but also makes the stability of the whole system worse. Other faults in the series. The main reasons for inducing such faults are as follows: The first, hydraulic cylinder piston and the end cap are not well sealed, resulting in serious leakage inside and outside the cylinder. The reason why the hydraulic system can realize the function is that the hydraulic cylinder pressurizes the liquid to make the piston or the end cap seal malfunction. The liquid inside the hydraulic cylinder will leak, and the internal pressure becomes lower. The beach is doing normal external work, resulting in a significant reduction in the efficiency of the hydraulic system or even complete paralysis. The second, the relief valve regulates insufficient pressure. The main function of the relief valve is to control the hydraulic system's functional force by adjusting the relief valve to control the outward output of the pressurized liquid when the liquid in the hydraulic cylinder is pressurized to the working pressure. If there is a problem with the pressure regulation, the adjustment is generally low, so that the other parts do not get the energy required for the normal working step, and then the problem that the sliding force of the slider is insufficient and the return speed is slow. However, if the adjustment is too high, the wear of the slider will increase and the damage to the hydraulic system will be more serious. The third, the surface of the male valve spool is severely worn, resulting in a tight closure at the valve port. The cone valve is a key part of maintaining hydraulic stability in the system and is a “sturdy line of defense” that blocks internal and external pressure exchange. If the cone valve spool fails, it will cause leakage of internal high pressure liquid and a slider failure. The surface of the valve body of the fourth reversing valve is worn, which makes the movement of the valve core difficult in the valve body. The one-way closing of the valve is not strict or the gap between the valve surface and the valve body is too large. As a result, the leakage of internal pressure will also cause the slider to malfunction.
Immediately after the failure of the hydraulic operating system, stop the fault finding, determination and maintenance work. For the detection of faults, there are mainly the following methods, the first method. The observation method is mainly for the pressure gauge and the hydraulic cylinder on the hydraulic control system to check whether the indication pressure of the hydraulic gauge is normal, thereby determining the cause of the failure and the orientation of the failure. The observation of the hydraulic cylinder is mainly to determine whether the hydraulic cylinder leaks. Because the leakage of the liquid leaves a very visible trace or is accompanied by sound. If the hydraulic gauge is low or there is a trace of obvious leakage, it can be determined that the hydraulic cylinder is faulty, and repair work can be taken immediately. The second fruit was observed and found no obvious faults or faults could not be directly observed with the eyes, such as the poppet valve core wear, such as the bead must use the instrument for detection such as optical imager, particle beam flaw detector. This type of instrument can detect faults such as misalignment or wear inside the hydraulic system by emitting high-energy particles.
Since the hydraulic cylinder is the core of the entire hydraulic control system, maintenance measures must be taken once liquid and pressure leaks out there. In general, two methods of welding and replacement are adopted. The welding method is mainly for the slight cracks or small holes in the hydraulic cylinder. In the welding, the combination of internal and external welding should be adopted to ensure the welding is complete. In particular, it must be noted that during the welding process, it is necessary to pay attention to eliminate the residual stress, otherwise the damage to the welding joint will be very large. If not handled properly, not only can the failure be repaired, but the failure will be more serious. The replacement method only needs to replace the defective hydraulic cylinder fittings. However, this method of disposal is simple but costly. This method of disposal is only possible when there is a large failure that is difficult to repair in a short time.
The hydraulic system of the hydraulic bending machine is complicated, so the troubleshooting work is also difficult. The face repair personnel must have deep knowledge to understand the hydraulic machine's work flow and have superb maintenance skills so that the fault can be quickly detected and given in a short time. eliminate.