As a key component of power machinery, the integral impeller is widely used in aerospace and other fields. The profile of the impeller blades is very complex, has a great impact on engine performance, has a long design and development cycle, and has a large manufacturing workload. Its processing technology has always been regarded as an important issue in the manufacturing industry. The traditional processing technology adopts a split machining scheme, that is, the blades and the hub respectively adopt different blanks, and the blades are welded to the hub after being separately formed. This solution is not only time-consuming and laborious, but also difficult to guarantee the performance indicators of the impeller.
With the continuous development of high-speed milling technology, multi-axis, especially five-axis CNC machine tools and CAM technology, the application of five-axis CNC machine tools for impeller machining can ensure that the ball head portion of the tool can accurately cut the workpiece and can use it. The rotating shaft works to avoid interference or overcutting of the cutter body or the shank portion of the tool with other parts of the workpiece, which fully satisfies the requirements for the production of the impeller parts.
For the impeller machining program generated after CAD/CAM processing, the interference inspection and program trial cutting of the tool path must be performed before the impeller is formally processed. The purpose is to verify and verify the correctness of the NC program, thus producing virtual reality technology simulation technology, which can fully reflect the real processing environment and processing process, such as workpiece clamping positioning, machine tool adjustment, cutting parameter selection. , comparison of processing results and design results; at the same time, early warning of collisions and interferences occurring during processing. Therefore, the practicality of the field workers, clamps, tools, etc. is reasonably evaluated, and the processability of the products, tooling, and the rationality of the process specifications can be evaluated, which is also required by the process and programmers.
Impeller processing technology analysis
The impeller structure can be divided into a hub curved surface and a blade curved surface. The blade includes a covered curved surface, a pressure curved surface and a suction curved surface, as shown in FIG. 1 . The impeller hub surface is formed by the blade neutral surface root curve and the blade neutral surface top curve around the Z axis; the design reference plane passing through the rotating axis Z is the meridional plane; the neutral plane is at the middle of the blade pressure surface and the suction surface. Surface.
Wide application of impellers in aerospace and other fields
It can be seen from the structural characteristics of the overall impeller that there are many constraints on the tool path planning when machining the integral impeller, and the space of adjacent blades is small. It is easy to generate collision interference during machining, and it is difficult to automatically generate the non-interference tool path.
The machining difficulty of the overall impeller is as follows:
(1) The impeller processing flow channel is narrowed, the blade is relatively long, and the rigidity is low. It belongs to thin-walled parts and is easily deformed during processing.
(2) The blade depth at the narrowest point of the flow channel exceeds 9 times of the tool diameter. The adjacent blade space is extremely narrow. The tool diameter is small during the clear angle machining, and the tool is easy to break. The cutting depth control is also the key technology of machining.
(3) The impeller surface is a free-form surface (including small blades and narrow flow channels), and the blade distortion is relatively serious, and it is easy to cause interference during processing.
This project uses the Mikron UCP800DURO five-axis linkage machining center to complete the finishing of the impeller.
According to the results of the process analysis and the five-coordinate finishing equipment used, the selected case of the subject--the processing route of the impeller is: blank → car machining meridian surface → five-coordinate finishing. For the blade and the round corner, the five-coordinate device is used for one-time machining, which not only ensures the continuity of the cutting of the tool path, but also ensures the precision of the blade and the rounded corner and the connection between the blade and the rounded corner. Divided into: waste processing channel → blade waste processing → blade semi-finishing → runner semi-finishing → blade finishing → runner finishing.
This topic uses UGNX4.0 to process the trajectory planning and NC program of the whole impeller.
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