June 22, 2021

Research on Numerical Control of Impeller of Engine Compressor

Determining the blank and the clamping position of the process plan First, the blank of the aluminum alloy is forged and processed into the basic shape of the rotor as shown. The intersection of A and C axes is defined as the machine origin, and B is the programming origin. Use the three-jaw self-centering chuck to clamp the D end, position it at A, measure E with the measuring probe, and make the Z axis of the impeller within the error range of the C axis center of the machine tool by repeated adjustment; measure C at the measuring probe, pass Repeat the adjustment so that the impeller is parallel to the XY plane. Tool selection The tool selection is based on the curved surface design requirements of the impeller vane channel. The principle of choice is to choose a large diameter tool as far as the hub channel can pass.

The impeller milling process is arranged for grooving. In order to improve efficiency, the impeller is slotted for stratified milling. Firstly, the 8mm short knife with larger diameter is selected to carry out rough machining of the upper and lower slots of the blade. The feed speed is 800mm/min, the spindle speed is 4000r/min, the cutting mode is down-milling, and the 8mm long knife is selected for import. The lower groove of the outlet is roughed, the feed speed is the tool diameter/mm, and the taper of the cutter head is used to rough the middle upper groove of the blade. The feed speed is 400mm/min, and the spindle speed is 6000r/min. It is proved that the groove roughing should be selected. The solid carbide flat end mill is milled from the center of the blank to the outer edge, and the groove bottom and the hub surface should be left with a certain machining allowance.

The milling hub selects a 1.85mm tool for machining the blade hub. The feed speed is 300mm/min, the spindle speed is 7000r/min, and the pass mode is the inlet triangle slot. Since the surface of the finishing wheel hub (ie, the bottom surface of the air flow passage) is processed by the point, the surface of the wheel hub is left with a knife mark, which is exactly what the designer requires, but the consistency of the tool mark should be paid attention to, and the consistency of the tool mark is proved by practice. Affect the overall performance of the impeller.

Blade inlet and outlet tipping According to the requirements of the design drawings, the 1.85mm tool is selected to chamfer and sharpen the inlet and outlet of the impeller blade. The blade profile finishing selects a 1.85mm tool for roughing and finishing the blade's side edges. Due to the side edge machining of the finishing mill blade, the leaf shape finishing and root cleaning processing should be completed in one process, so that there is no knife mark on the surface of the blade, the surface processing consistency is good, and the surface roughness value can reach Ra= 3.2mm or more.

Conclusion (1) For the NC machining of variable surface and semi-open compressor impellers, the difficulty lies in the analysis of the process plan based on the complex changes of the blade-shaped surface, selecting the reasonable machining tool and machining path, and determining the selection according to the design requirements. Side-edge machining is also a free-form surface machining, and the accuracy and surface roughness are controlled within the allowable error range. By optimizing the machining tool path, the machining time is reduced as much as possible while avoiding the vibration of the tool and the blade. (2) Using the current CAD/CAM technology for computer modeling, NC programming and VERICUT software simulation processing simulation technology, the production development cycle is short, the processing precision is high, and the safety and reliability of the processing process are more guaranteed. Become the goal pursued by the modern machinery manufacturing industry. (3) The hub and the blade are processed on the blank once in the five-axis machining center. The measurement of the coordinate measuring machine shows that the actual machining surface is very close to the curved surface required by the design, with small error and high precision. It also has less weight and is one of the most ideal machining methods for milling integrated impellers.

(Finish)

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