Mistake Of Using Mechanical Seal Ring In Hydraulic Cutting Machine

- Oct 16, 2019-

The flow rate of hydraulic pump of hydraulic cutting machine refers to the volume of liquid discharged in unit time, including theoretical flow rate, actual flow rate and rated flow rate.Let's call it q, in units of L/min.


Theoretical flow q1.The theoretical flow rate is the volume of liquid displaced per unit time regardless of the leakage flow rate of the hydraulic pump.However, if the displacement of the hydraulic pump is V and the spindle speed is ", then the theoretical flow of the hydraulic pump is q1=Vn


Actual flow qp.Actual flow is the hydraulic pump in the work, consider the leakage of the hydraulic pump output flow.It is equal to theoretical flow minus leakage flow delta q.


Rated flow rate qn rated flow rate refers to the flow rate that the hydraulic pump must guarantee under normal working conditions as stipulated in the test standard (such as rated pressure and rated speed).Both the actual flow and the rated flow are less than the theoretical flow.


We know from physics that liquid has two important properties.The cutting machine fluid is almost incompressible;The pressure of a stationary liquid in a closed container is transferred in all directions with equal force.When the handle is moved upward with the hand, the small piston moves upward to increase the closed volume cavity at the lower end of the small piston, forming a vacuum.Under the action of atmospheric pressure, oil enters the lower chamber of the small oil cylinder through tubing 5 and one-way valve 4.Push down the handle, the small piston moves down, the oil in the closed volume chamber is squeezed, and the oil in the lower chamber is fed into the lower chamber of the large cylinder through pipeline 6 and one-way valve 7 (at this time, one-way valve 4 is closed and cut off from the oil in the oil tank), forcing the big piston 8 to move up to lift the weight W.


Installation method varies with mechanical seal type and type of machine, but the installation essentials are almost the same. Installation steps and precautions are as follows:


During installation, the installation size of the mechanical seal should be guaranteed according to the product manual or sample.


Before loading, the shaft (shaft sleeve), gland should be no burr, the bearing is in good condition;Seals, shafts, seals and gland should be cleaned.To reduce friction resistance, the installation of mechanical seals on the shaft should be thin coated with a layer of oil, in order to lubrication, consider the rubber O ring compatibility, if not suitable for oil, can be coated with soapy water.Floating type static ring without the structure of anti-transfer pin, not suitable for oil, should be dry into the gland.


Install the stationary ring and gland on the shaft first, be careful not to touch the shaft, and then load the moving ring assembly.The set screw of the spring seat or transmission seat should be tightened evenly several times.


Before fixing the gland, push the compensation ring by hand for axial compression. After loosening, the compensation ring can automatically spring back to the absence of stagnation, and then lock the gland screw bolt evenly.


The sealing effect of the new cutting mechanical seal is better than the old one, but the quality or material selection of the new mechanical seal is not at the right time.In aggregates and permeable media, static ring such as no excessive wear, is still not replaced for good.Because the stationary ring is in the stationary ring seat for a long time, the polymer and impurity deposit as a whole, which has a better sealing effect.


If the quality of the hydraulic oil is qualified, the movement speed of the system actuator is very high, the flow rate of the oil is also high, the hydraulic loss increases, and the leakage is relatively reduced, so it is advisable to choose the oil with lower viscosity;On the contrary, when the oil flow rate is low, the leakage is relatively increased, which will affect the movement speed of the working mechanism, which is appropriate to choose the oil with higher viscosity.Generally, when the working pressure is high, it is advisable to choose the hydraulic oil with high viscosity, because solving the leakage problem when the high pressure is higher than overcoming the viscosity resistance.When the working pressure is low, it is advisable to choose low viscosity oil.When the ambient temperature is high, oil with higher viscosity should be used.Instead, use a lower viscosity oil.