Jan 07, 2020
3.Five-axis high-speed milling tool rail planning and design
Five-axis CNC high-speed cutting has more special technological requirements than traditional cutting methods, because in addition to the high-speed cutting machine itself and high-speed cutting tools, you should also choose a suitable professional CAM programming program. CAXA manufacturing engineers are typical representatives of domestic production. CAM programming parts, to achieve a full range of CNC machining solutions from CNC machining to modeling design and machining code generation, simulation machining, code verification, etc., with support for multiple CPU hardware platforms, multi-task trajectory calculation and management, multi-processing parameter selection Multi-axis machining function, multi-tool type support, multi-axis solid simulation and other six advanced comprehensive performance.
The key point of the trajectory planning and design of the 5-axis tool is that before designing the tool machining trajectory path, it is necessary to set the accuracy as high as possible in the 3D model designed by the CAD software. Sometimes, the designed 3D The model is used for data conversion and processing between different CAD software. Before processing, the data must be converted in CATIA or Parasolid format first, and then the data can be converted in IGES format. CAXA manufacturing engineers provide five-axis isoparametric lines, five-axis curve processing, five-axis side milling, five-axis curved surface area processing, and five-axis G01 drilling, five-axis orientation, and four-axis trajectories.For impellers and blades, In addition to the above-mentioned machining methods, the system also provides dedicated roughing and finishing of the impeller, which can realize the overall processing of the impeller and the blade.
4.Process analysis of impeller
The impeller structure is mainly divided into two parts, namely, the curved surface of the blade and the curved surface of the hub, and the curved surface of the blade includes a curved surface, a pressure surface, and a suction surface. In the milling process of five-axis CNC high-speed machine tools, the machining of the blade surface can be divided into two types: "line contact (side milling)" and "point contact." For side milling, the entire side of the machining tool is processed. The edge is in contact with the contour line of the blade to be processed. For thin blades, the springback effect during processing is still very large, so when we generally mill this type of blade by side milling, we usually take an approximate processing method. For point contact parts, it is not easy to adopt this kind of processing method, because if the blades are relatively curved, there may be relatively close spatial distances between the blades, so they may appear adjacent to each other during processing. The phenomenon of interference between blades; however, "point processing" is relatively smaller than the "spring processing" of springback during processing of such thin blades. Therefore, when processing rounded corners, most of them use "point processing". Processing methods.
In this case, the contour of the overall impeller surface is a free-form surface. At the time of design, due to the narrow flow channel, the blade distortion is relatively serious, and there is a clear tendency to recline. It also easily interferes during processing, which increases the difficulty of processing coefficient. However, there are some impellers, because of the existence of auxiliary blades, in order to avoid interference during processing, they need to be processed in sections. The basic processing process is:
(1) Forging aluminum to form wool forgings.
(2) Turning rough forgings.
(3) Roughing runner.
(4) Semi-finished runner.
(5) Blade finishing.
(6) Finishing flow path.
(7) Clear the rounded part.
The modeled impeller part model can be imported into the CAM part of the CAXA manufacturing engineer for simulation processing, or 3D solid modeling can be performed directly in the part design part of the CAXA manufacturing engineer.
Impeller machining parameter settings
In this example, the CAM function department of the CAXA manufacturing engineer is mainly used to simulate the five-axis machining. In the real-time process, for the complex special curved surface of the impeller, the CAXA manufacturing engineer provides two special machining solutions, namely rough machining of the impeller and finishing.
Rough machining of impeller
Specific parameter setting method: First select the "Processing"-"Multi-axis machining"-"Impeller roughing" menu in the menu bar of the CAXA manufacturing engineer, and the system will pop up the "Impeller roughing" dialog box, select the impeller roughing, cutting amount and tool parameters On the tab page, set the corresponding processing parameters as shown in the picture. For rough machining, set the machining allowance of the bottom surface of the impeller to "0.3" and change the "machining accuracy" to "0.1", thereby reducing the calculation time of the tool path and reducing the amount of programs, and the machining allowance of the blade surface is set to "1". For rough machining, set the machining allowance of the bottom surface of the impeller to "0.3" and change the "machining accuracy" to "0.1", thereby reducing the calculation time of the tool path and reducing the amount of programs, and the machining allowance of the blade surface is set to "1".
CAXA provides two machining strategies. Here, the impeller finishing strategy is used to create the blade finishing tool trajectory according to the corresponding settings. The machining reserve is "0.2".
Blade finishing and runner finishing
Enter "0.01" on the "Floor Finishing Allowance" on the "Blade Finishing Parameters" tab, and predefine the ball-end milling cutter as "R4" on the "Tool Parameters" tab and set it as the processing tool. In the Impeller Finishing dialog box, set the indexing angle parameter to 45.
Generate NC code
① Set the parameters first: Click "Processing"-"Post-processing 2"-"Post-setting", and determine the relevant parameters of the CNC system and the program code according to the processing equipment used, because the CNC system file list does not include those involved in this article. The type of machine tool and other programmed CNC system files are in accordance with the regulations and need to be modified and reset.
② According to the mechanical structure of the five-axis machine tool, select "Dual table" in the machine tool structure type, select "C axis" for the rotation axis, the maximum angle of the rotation axis is 99999, the minimum angle of the rotation axis is -99999, and the minimum angle of the swing axis is "-90. ", Other existing content can meet the requirements of the program structure of this artifact. Remember not to modify or re-fill.
③NC code generation: Click "Processing"-"Post processing 2"-"Generate G code" first, click the system will pop up the "Generate post code" dialog box, and set the file name to the specified sequence number (such as: 0004), click the "OK" button, the current screen status bar will prompt to pick the tool track, click the tool track (the state becomes red), right-click to confirm the completion of G code output.