Coupling assembly is the key to the pump, mechanical maintenance belongs to a relatively simple maintenance process. But many are not very good. In the coupling assembly, it is crucial to grasp the assembly of the hub on the shaft, the alignment of the two shafts coupled by the coupling, the inspection of the components and the assembly of the coupling according to the drawings. How to assemble the hub on the shaft One of the keys to the coupling installation when assembling the hub on the shaft. Mostly with the hub and shaft interference fit, the connection is divided into a key connection and keyless connection, the hub of the shaft hole is divided into two kinds of cylindrical shaft hole and tapered shaft hole. Assembly methods are static pressure method, dynamic pressure method, temperature difference assembly method and hydraulic assembly method, etc. (1) The pump static pressure method This method is based on the assembly of the hub shaft required pressure force into the different sizes , Using clamps, jacks, manual or motorized presses, static pressure method is generally used for tapered shaft hole. Due to the static pressure method to receive pressure machinery restrictions, in the larger interference, the application of great force more difficult. At the same time, in the process of press-in will be cut off between the hub and the shaft with uneven surface of the tiny peaks, so that the mating surface is damaged. Therefore, this method is generally not much used. (2) Pump power injection method Pump assembly This method refers to the use of impact tools or machinery to complete the assembly process of the hub to the shaft, generally used between the hub and the shaft With the transition or interference is not the occasion. At the assembly site, the usual method of hammering with a hand hammer is to cushion the block, lead block or other soft material on the end face of the hub and knock the wheel in by relying on the impact of the hammer. This method of using cast iron, quenched steel, cast alloys and other brittle materials made of the hub, there is the risk of local damage, should not be used. This method also damage the mating surface, it is often used for assembly of low-speed and small coupling (3) pump temperature difference assembly method of heating the pump assembly is the hub by thermal expansion or cooling method to the shaft end cold shrink , So that the hub bore diameter slightly larger than the diameter of the shaft end, that is to achieve the so-called "easy assembly value", do not need to exert a great force, you can easily set the wheel hub to the shaft. This method is more than the static pressure method, dynamic pressure method has many advantages, for the hub made of brittle materials, the use of temperature difference assembly method is very suitable. Pump assembly temperature difference method are mostly used to install the heating method, cooling The method used less. There are a variety of heating methods, and some will put the hub into the flash point of oil for oil bath heating or welding torch baking, and some use the oven to heat the assembly site to use oil bath heating and torch baking. Oil bath heating can reach the maximum temperature depends on the nature of the oil, usually below 200 ℃. When the hub is heated by other methods, the temperature of the hub can be made higher than 200 ° C. However, the heating temperature of the hub can not be arbitrarily increased from the viewpoint of metallography and heat treatment. The recrystallization temperature of the steel is 430 ° C. If the heating temperature exceeds 430 ℃, it will cause changes in the internal structure of steel, so the upper limit of the heating temperature must be less than 430 ℃. For the sake of insurance, the upper limit of heating temperature should be below 400 ℃. The actual heating temperature of the hub can be calculated according to the interference between the hub and the shaft and the requirements of the hub after heating to the shaft. (4) Inspection after assembly of the pump The hub of the pump assembly coupling is on the shaft After the assembly is complete, should carefully check the hub and shaft verticality and coaxiality. Generally, two dial indicators are arranged on the end surface and the outer circumference of the hub. When the disk drive rotates the shaft, the value of the full run-up (including the end runout and the radial runout) of the hub is observed to determine the perpendicularity between the hub and the shaft and the coaxiality Degree of the situation. Different speeds of the coupling requirements of full beating different, different types of coupling requirements for full beating also vary, but after the assembly of the hub in the shaft, you must make the hub full runout deviation in the This is one of the main quality requirements for the coupling assembly within the tolerances of the design requirements.There are many reasons why the full run-in value of the hub can not meet the requirements of the pump assembly. Firstly, it may occur during manufacture due to machining errors. Said that mainly due to improper handling of the bore surface in the hub, the concentricity of the hub and the shaft deviates. Another reason is that when a keyed shaft coupling is assembled, the hub and the shaft are not coaxial due to incorrect key assembly. The correct installation of the key should make both sides of the key and the keyway closely fit the wall, usually with the paint color inspection assembly, with the bad file can be used to repair the file or blade to meet the requirements. The upper part of the key generally gap, about 0.1-0.2mm or so. High-speed rotating machinery requires high concentricity of the hub and the shaft, can not obtain high concentricity with a single-key connection, and the concentricity of the two can be improved by using the double-key connection or the spline connection. Before the installation of coupling parts clean, clean parts, the need to dip in the wash oil dry. In a short period of time to prepare for the operation of the coupling, dry the parts surface can be coated with turbine oil or oil, to prevent rust. For couplings which need to be used for a long time, they should be coated with anti-rust oil. There are many types of structures for assembling pumps in Pacific Pumps. The requirements and methods of assembly are different. For the installation, The principle is strictly in accordance with the requirements of drawings assembly, the specific can only introduce some of the coupling assembly often need to pay attention to the problem. For high-speed rotary machinery used in the coupling, usually in the factory have done the balance test, after the dynamic balance test is drawn on the parts of each other with the coordinates of the marker. It is important that the assembly be made with the marking given by the manufacturer. If not assembled according to the mark, it is likely to occur due to poor dynamic balance of the unit caused by vibration of the unit.In addition, the coupling flange bolts on the load-bearing, so that each coupling The coupling bolts on the weight can be done basically the same. Such as large-scale centrifugal compressor gear coupling used, the bolts used in their mutual weight difference is generally less than 0.05g. Therefore, the bolts between the couplings are not interchangeable. If one of the coupling bolts is to be replaced, the weight of the coupling bolts must be the same as that of the original coupling bolts. In addition, when tightening the coupling bolts, the coupling should be symmetrical and gradually tightened so that the locking force on each coupling bolt will be basically the same, so that the coupling will be skewed after assembly due to the uneven force of the bolts Phenomenon, the conditional torque wrench can be used.For the rigid removable coupling, after assembly should check the rigid coupling can move a small amount of movement, with or without jamming phenomenon. After assembling the axles, they should be cranked to see if the rotation is good. In short, the correct installation of the coupling can improve the operation of the equipment, reduce the vibration of the equipment and prolong the service life of the coupling.How to assemble and disassemble the coupling in the pump assembly is the opposite process different. Assembly process is assembled according to assembly requirements of the coupling, so that the coupling can be transmitted safely and reliably torque. Disassembly is generally due to equipment failure or coupling itself needs maintenance, the coupling disassembled into parts. The degree of demolition is generally based on maintenance requirements, and some simply require the coupling of the two axes off, and some not only to the coupling of all its decomposition, but also the hub removed from the shaft. There are many types of couplings, different structures and different disassembly processes of couplings, and some problems needing attention in the disassembly of couplings are mainly introduced here. Since the coupling itself needs to be disassembled, firstly To the whole coupling to do careful examination (especially for the shaft has been damaged), should identify the cause of the malfunction in the coupling before demolition, to the coupling between the various parts of the position for Some markings, for refitting when the reference. Couplings for high-speed machines, the coupling bolts weighing, marking must be clear, can not make mistakes. Pump assembly Demolition of the coupling is generally the first demolition of bolts. As the thread surface deposits a layer of grease, corrosion products and other deposits, the bolt is not easy to disassemble, especially for the rusty bolts, disassembly is very difficult. The removal of the coupling bolts must be made with the right tool, since the force-bearing surfaces of the hexagon socket or hexagon socket of the bolt have been damaged by slippage and disassembly can be more difficult. For rusty or grease more bolts, often with a solvent (such as pine rust agent) spray bolt and nut joints, so that solvent penetration into the thread, so that it will be easy to disassemble. If you can not remove the bolt down, you can use heating method, the heating temperature is generally controlled below 200 ℃. By heating the nut and bolt to increase the gap between the rusty objects also easily fall, the Pacific pump pump assembly makes it easier to remove the bolts. If you do not use the above methods, only the destruction of bolts, the bolts cut off or drill off, in the assembly, the replacement of new bolts. The new bolts must be the same size as the original used bolts and must be weighed so that new bolts are replaced with new ones for high speed equipment couplings so that the new bolts will have the same weight as the coupling bolts on the same set of flanges During disassembly, the most difficult job is to remove the hub from the shaft. For the key to the hub, the general pull with a three-legged or four-legged Rama for disassembly. The selection of puller should be matched with the overall dimensions of the hub. The right-angled hook of the puller and the rear of the hub should be properly fitted so that no slippage can occur when force is applied. This method is only used for the interference of the smaller hub disassembly, for the larger interference hub, the Pacific pump pump assembly often used heating method, or at the same time with the hydraulic jack to remove all parts of the coupling to be cleaned, Cleaning and quality assessment is a very important work after the coupling is disassembled. The assessment of components means that after the operation of each component, the existing conditions of its size, shape and material properties are compared with the quality standards determined by the component design to determine which components can continue to be used and which components should be Used after repair, which parts belong to the parts that should be scrapped.
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