Use of simple tooling fixture and cutting temperature
Due to the thin wall and low strength of the module, if the clamping force is too large, it will warp; if the clamping force is small, the module is easy to loosen under the action of cutting force, which is dangerous. Therefore, more support platforms are added in the height direction, and pressed with a pressure plate at the support point, so that the module will not be deformed due to the clamping force. In order to control the deformation when processing large-scale thin-walled parts, improve processing stability and facilitate clamping, special simple clamps are specially designed. The special fixture used in this article is composed of several Z-type positioning brackets and the bottom plate. The Z-type positioning bracket is fixed on the bottom plate by bolts. First compile the NC program to ensure that the height drop between the positive and negative Z-shaped positioning brackets of the processing door module is consistent with the height drop of the precision reference platform and the supporting platform reserved by the processing module, and then naturally fix the door module on the Z-shaped positioning bracket. Then through the preparation of CNC program milling to ensure the Z-level height drop of the support column of the module (that is, the finishing reference), and finally use the lever meter to detect. After processing one side of the module, remove the module and place it in reverse, install another set of Z-shaped positioning brackets, and process the other side of the module in the same way.
This fixture can also place artificially aged or naturally aged thin-walled modules on the installed Z-shaped positioning bracket naturally. Use a feeler gauge to detect the gap between the Z-shaped positioning bracket and the reserved column module contact end surface to detect the module The maximum and minimum deformation in each direction; for the finished module, after removing the lifting bolts, you can use a feeler gauge to detect the actual deformation after processing for reference for subsequent processing and CMM final measurement.
The special tooling is simple and quick, reduces the clamping time and processing deformation, improves the processing stability and processing accuracy of thin-walled parts, and provides a quick deformation measurement method for thin-walled parts after processing.
2. Cutting temperature control and selection of machine tools and tools
(1) Cutting temperature control. The cutting temperature has a great influence on the machining. To control the influence of the temperature on the machining deformation during cutting, the finishing is placed in a constant temperature machining workshop. The cutting fluid uses oil-based cutting fluid. The instantaneous temperature of the machining can be controlled below 30 ℃ to avoid instantaneous oxidation of the material. To control the processing deformation.
(2) Machine tool selection. Roughing and semi-finishing are processed on a three-axis CNC machine tool with better rigidity and higher power. The finishing process adopts advanced large-scale five-axis CNC machine tools to perform fixed-axis overall processing to ensure that once clamping during finishing, it can be processed to all The parts ensure the position accuracy between the parts of the large thin-walled parts, and adopt a high-speed machining method with less back-cutting and lighter cutting to control the amount of deformation generated during finishing.
(3) Tool selection. In module processing, a reasonable tool angle is critical to the cutting force, cutting thermal deformation, and surface roughness. This article selects the overall alloy R angle milling cutter. The characteristics of this kind of cutter are:
①Ultrafine grain cemented carbide substrate;
②Adopt a 45° helix angle, and in order to increase the chip evacuation space, 2 or 4 edge milling cutters are often used;
③Unique bottom edge R-angle design, short shank, increased cutting strength, extremely sharp edge, to reduce extrusion processing, so as not to generate heat deformation;
④When finishing or processing the side walls, a hard alloy ball head cutter or end mill for sharp aluminum alloys must be used.