CBN tool turning machining of hard alloy materials Introduction: In addition to making tools, hard alloys can also be used as various wear-resistant and heat-resistant molds, such as tungsten carbide rolls, carbide punches, hard alloy wear-resistant bushings, etc. . The hardness of cemented carbide workpieces is about 69~81.5HRC, and some are up to 90HRC. For the machining of carbide workpieces, CBN tools can be used instead of electrophysical machining, diamond cutting and diamond grinding. The following are examples of the processing of cemented carbide materials by Hualing Superhard, and the precautions for CBN tool turning of carbide materials.
(1) CBN tool car outer circle: On the φ40mm, length 100mm carbide punch, cut the 3.5 mm margin, only 25min, if grinding with diamond grinding wheel, it will take 215min.
(2) CBN tool interrupted turning: not only can continuous turning of hard alloy, but also intermittent turning. For example, when turning the carbide sleeve of YG20 and YG25 intermittently, νc=30m/min, ap=0.35mm, f=0.034mm/r. The geometric parameters of the tool are: γo=-6°, αo=8°, κr=45°, and the durability of the tool is 65 min.
(3) Boring with a CBN tool: The hole is punched in a cemented carbide material bushing with an accuracy of IT6 to IT8 and a surface roughness Ra of 1.6 to 0.8 μm. The amount of cutting is: νc = 15 m / min, ap = 0.2 ~ 0.5 mm, f = 0.1 ~ 0.15 mm / r. The tool geometry parameters are: γo=-5°, αo=6°-8°, κr=45°, κ'r=15°, rε=0.5 mm. The efficiency of boring with a CBN tool is about 10 times higher than that of a diamond grinding wheel. )
(4) Disadvantages: When machining cemented carbide with CBN tool, the surface roughness is generally greater than 0.8μm. This is because the radial component force FP when cutting cemented carbide is large, causing the tool to retreat. When νc=10m/min, ap=0.5mm, f=0.1mm/r, flank wear 0.05mm, FP is about 400N; when VB=0.1mm, FP=700N; when VB=0.2mm, FP= 1300 N. Therefore, to cut cemented carbide with superhard tools, it is necessary to select the process conditions with good process system rigidity.
Precautions for CBN tool turning and machining of hard alloy materials
(1) Cemented carbide workpieces have high hardness and brittleness, and the cutting force is concentrated near the cutting edge, which is likely to cause tool chipping. In particular, the ordinary CBN cutter cut into the cut-out is extremely easy to collapse. It is more suitable to use the Hualing super-hard BN-S20 grade at a line speed of 15m / min; the normal failure state of the cutter should be the flank wear.
(2) When processing cemented carbide materials or tungsten carbide materials, the chips are all powdery, no built-up edge, and the processed surface roughness is easy to reach 1.6 μm, but it is difficult to exceed 0.8 μm. Summary: After trial cutting research, when machining workpieces made of cemented carbide materials with CBN tools, the processing cost can be greatly reduced, and the work efficiency is greatly improved; especially when the machining allowance of the workpiece is large, or when there is intermittent turning, the effect will be more obvious. If the surface finish is required to be less than 0.8 μm, the CBN tool for roughing can be considered, and then refined to improve work efficiency and reduce processing cost. (Zhengzhou Hualing Superhard Materials Co., Ltd. copyright, please indicate the source)
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