Cutter for deep groove milling of titanium alloy
Titanium alloy has a small elastic modulus and a small thermal conductivity coefficient, which is a typical difficult-to-machine material, especially when deep groove cutting is more difficult. Figure 1 shows an example of processing a deep groove with a width of 4 mm, a depth of 30 mm, and a length of 300 mm on a titanium alloy part.
For ordinary materials (such as 45 steel), high-speed steel (W18Cr4V) saw blade milling cutters (φ120×φ40×4, 60 teeth) are often used for machining the above deep grooves, and sufficient cooling is performed to obtain good milling results. However, for the titanium alloy TC4 material, when using the above-mentioned saw blade cutter to cut a blind slot with a depth of 30 mm, a new blade will wear when processing the first or second workpieces, and its cutting edge will become dull. Grinding, the squeeze in front of the cutting edge will increase significantly, the metal deformation in the cutting area will also increase, and at the same time, the back angle of the tool will continue to decrease after wear, thereby increasing the friction between the back of the tool and the processed surface, making Cutting heat increases, resulting in a sharp increase in cutting temperature. When machining the third part, the tips of the two sides of the teeth of the teeth were obviously burnt out, especially the titanium chips were stuck in the back of the teeth and the chip pockets, indicating that severe extrusion occurred during the cutting process. This is because in addition to the small thermal conductivity and thermal conductivity coefficient of the titanium alloy and the large friction coefficient between the titanium alloy material and the tool material, the cutting temperature rises rapidly, and there are also difficulties in chip evacuation due to the insufficient chip pocket. If the above-mentioned worn blades are sharpened, the burnt tip should be completely polished out, and the diameter of the blade should be polished off 3 to 4mm. In this way, the number of sharpening times of a tool will be greatly reduced, resulting in chip tolerance The slot becomes smaller. Practice shows that the blade after such sharpening can only process at most one part. For this reason, in the study, the new blade was tried to jump teeth to increase the chip space of the milling cutter. It was found that this method can increase the life of the cutter by about 3 times, and each blade can process 5 parts. This tool can meet the needs of scientific research and trial production, but it cannot meet the requirements of mass production.
Using the method of skipping the blade milling cutter, the life of the blade milling cutter used for milling titanium alloy TC4 can be significantly improved. This method can reduce the friction between the tool and the titanium alloy material, and can increase the chip space, but the potential of this method is limited. From the perspective of production efficiency and cost, it is necessary to design carbide (YG15) welding tools and high-speed steel (W6Mo5Cr4V2Al) welding tools.
Carbide welding tools and high-speed steel welding tools were used to test the grooving of the above workpieces (the same cutting conditions). The high-speed steel welding tools can process 6 parts, while the YD15 welding tool can process 30 parts. Comprehensive saw blade milling cutter and skip tooth saw blade milling cutter are tested under the condition that the cutting amount is ap = 7mm, f = 0.3mm/r, v = 26m/min, and the wear between the tool and the number of grooves can be obtained Relationship.
In the deep groove milling of titanium alloy, the wear of the tool is mainly related to the tool material. For titanium alloy, which is difficult to machine, fine grain hard alloy material should be preferred, which can greatly improve its processing efficiency and processing quality. In addition, the structure of the cutting part of the tool is also very important. It is necessary to consider that the cutter teeth have a large chip space, and also consider the selection of a reasonable number of teeth to improve the machining efficiency. Therefore, we choose 4 or 6 tooth carbide welding slot milling cutter to meet the requirements of titanium alloy deep groove batch processing.
The test shows that for the deep groove milling of titanium alloy, the life of the cutter is increased by 3 times compared with the conventional saw blade milling cutter; the use of YD15 carbide welding milling cutter can significantly improve the tool life.