Slow wire walking, also called low-speed wire walking, is a kind of CNC machining machine tool that uses continuously moving fine metal wire as an electrode to pulse spark discharge on the workpiece to generate a high temperature of over 6000 degrees, ablate metal and cut into a workpiece. The principle of wire processing is the phenomenon that there is a gap between the wire electrode and the workpiece, and the metal is removed by continuous discharge. Since the slow-moving wire cutting machine adopts the method of wire electrode continuous feeding, that is, the wire electrode is processed during the movement, so even if the wire electrode is worn out, it can be continuously supplemented, so it can improve the machining accuracy of the parts and slow the wire. The surface roughness of the workpiece processed by the cutting machine can usually reach Ra=0.8μm and above, and the roundness error, linear error and dimensional error of the slow-moving wire cutting machine are much better t
1. Blue-collar layer: That is, CNC machining operation technicians, proficient in machining and CNC machining process knowledge, proficient in the operation and manual programming of CNC machine tools (attributes: automated machine tools), understand automatic programming and simple maintenance of CNC machine tools (attributes: automated machine tools), such There is a large market demand for personnel, and they are suitable for operating workers of CNC machine tools (attributes: automated machine tools) in the workshop, but due to their single knowledge, their wages will not be much higher. 2. Gray collar layer: One, CNC machining programmer: Master the knowledge of 5 Axis CNC machining Aluminum technology and the operation of CNC machine tools (attributes: automated machine tools), be familiar with the design and manufacturing expertise of complex molds (title: mother of industry), and be proficient in 3D CAD/CAM software, such as UG, GOOGLE PRO/E, etc. ; Familiar with CNC
The static pressure slide rail (TTW guide) of the CNC machining lathe transfers the oil with a certain pressure through the throttle to the oil cavity between the sliding surfaces of the slide rail (TTW guide) to form a pressure oil film to float the moving parts , Make the sliding rail (TTW guide) surface in a pure liquid friction state. CNC machining General CNC machining usually refers to computer digital control precision machining, CNC machining lathe, CNC machining milling machine, CNC machining c17200 beryllium copper and milling machine, etc. The feed route of finishing is basically carried out along the part contour sequence. Therefore, the focus of determining the feed route is to determine the feed route of rough machining and idle stroke. In the numerical control processing, the control system issues instructions to make the tool perform various motions that meet the requirements, and the shape and size of the workpiece are expressed in the form of numbers and lette
Aerospace engines are known as the jewel in the crown of modern industry. Their output power is amazing. Aero engines weighing only a few tons can propel passenger planes weighing dozens of tons and hundreds of tons. Generally speaking, the manufacturing cost of aero-engines accounts for about 30% of the total manufacturing cost, and the importance is self-evident.
The internal structure of aero-engines is very precise and complex, and the connections between parts should be tightly connected. But when passing by the aircraft engine, a rattling sound can be heard from inside. Could it be that the fan blades inside the engine are loose? That’s right, it’s loose, but don’t be afraid, it was originally designed like this.
The aero engine completes the compression and expansion of the gas, and generates powerful power with the highest efficiency. The blade that drives the aircraft forward is a special part with a large number of complex shapes, high requirements, and difficult processing.
The curved configuration of aero-engine blades is extremely complex, which transmits considerable torque and extremely high combustion temperature. Therefore, the material of the blade is generally made of high-temperature resistant and high-strength materials. The initial material was a polycrystalline nickel-based superalloy. Later, a polycrystalline blade with oriented grain boundaries was made. The crystalline direction was consistent with the force direction, and the performance was improved a lot. Finally, it developed to the widespread use of titanium alloy materials. Integral blade processing technology.
As the load-bearing component of the engine, the blades of these fans are not firmly fixed on the engine, but are stuck in the tongue and groove of the fan disc through the tenon. There is a gap between the tenon and the groove. When the fan rotates slowly, under the action of gravity, each blade will slide toward the axis when it is close to the twelve o’clock position, and when it is close to the six o’clock position, it will move towards The axis slides out in the opposite direction. As a result, the fan blades collided with each other in the process of slashing to and fro, making a rattling sound.
The mortise and tenon structure connecting the fan blades and the fan plate is called a “vertical tree” mortise, because it looks like a vertical tree and a fir tree, showing a toothed V-shaped tenon and a groove between the tenon and tenon. The obvious gap can facilitate the free sliding of the tenon within a certain range.
Why are aero engine blades designed as loose structures?
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When the engine fan rotates rapidly and exceeds the critical speed, the rotating shaft begins to approach its geometric center due to its elasticity, and then crosses the geometric center and approaches its imbalance. At this time, the direction of the centrifugal force received by the blade starts from the new rotating shaft and passes through the position of the blade. The component along the tangential direction of the turbine disk points to the opposite direction to the unbalanced position, which makes the blades deviate in this direction, thereby re-adjusting the unbalanced position so that the center of gravity is close to its geometric center, thereby reducing vibration.
This process is dynamic, so the vibration of the fan at any high speed can be dynamically reduced, and the angle of the blades relative to the tangential direction of the turbine disk changes periodically, so the blades need to swing left and right.
In order to allow the blades to swing freely to a certain extent, the blades are not completely fixed on the turbine disk, but are left with gaps, and the shoulders cannot be completely close to the adjacent blades, which is also to allow the blades to swing. It is certain that not only the blades of the fan are loose, but the blades of the entire compressor are all loose.
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