In the processing of the most difficult cutting ma

2022-08-09
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Machining of difficult to cut materials (middle)

3. Turning of superalloys

because superalloys contain many high melting point alloy elements Fe, Ti, Cr, Ni, V, W, Mo, etc., these elements and other alloy elements form austenitic alloys with high purity and dense structure. The elements with C, B, N and other non-metallic elements constitute metal and non-metallic chemical compounds with high hardness, low specific gravity and high melting point. Make other machinability become very poor. Its relative machinability is only 5 ~ 20% of 45 steel

① cutting characteristics: 1) large cutting force: 2 ~ 3 times larger than cutting ordinary steel. 2) High cutting temperature: 50% higher than cutting 45 steel. 3) Severe work hardening: the hardness of the cutting surface and the machined surface is% higher than that of the substrate. 4) The tool is easy to wear: it is easy to produce adhesion, diffusion, oxidation and groove wear

② tool material: 1) high speed steel: high vanadium, high carbon, aluminum containing high speed steel should be used. 2) Cemented carbide: YG

of fine and ultra-fine particles should be used ⑨ geometric parameters of cutting tool: deformed superalloy: 0=10, cast superalloy: 0=0, generally no negative chamfer. 0=10 ~ 15, rough turning s =-10, fine turning s =0 ~ 3, r=45 ~ 75

④ cutting amount: 1) high speed steel tool: vc=3 ~ 8m/min. 2) Carbide tool: vc=10 ~ 60 m/min. Deformed superalloy: vc=40 ~ 60m/min. Cast superalloy: vc=7 ~ 10m/min. P and f 0.1mm

⑤ cutting fluid: the same as stainless steel

⑥ high temperature alloy drilling: cemented carbide drill or S-type and shallow hole drill should be used as far as possible; For example, when using high-speed steel drill, increase 2 towels, grind 0 and B, VC is 3 m/min, f is 0.2 ~ 0.3mm/r; The drill bit should be sharp and blunt. The standard is 1/2 ~ 1/3 of general steel. It is best to use automatic feeding and do not stay on the cutting table

4. Turning of titanium alloy:

titanium alloy is a new metal developed in recent decades. Because of its high specific strength (B/=1680/4.5=373, 4.5 times that of 45 steel), high thermal strength (long-term operation at 500 ℃), good corrosion resistance and excellent low-temperature performance, it is used in aerospace, chemical industry, medical treatment, etc

① cutting characteristics: 1) high cutting temperature: under the same cutting conditions, it is twice as high as cutting 45 steel. 2) The affinity is large, and the bonding is serious, resulting in the bonding phenomenon at high temperature. 3) High chemical activity: under high-temperature cutting conditions, it easily reacts with O, N, h and C in the air to produce hard coatings such as TiO2, tin and TIH, which brings difficulties to cutting

② tool material: 1) high speed steel: in addition to ordinary high speed steel, it is best to choose high vanadium, high cobalt and aluminum containing high speed steel. 2) Cemented carbide: YG8, YG6X, yg6a, 813, 643, ys27, yd15.3) PCD, PCBN natural diamond

③ tool geometric parameters: 0=5 ~ Jinan Shidai torsion testing machine machine machine inspection 15, 015

④ cutting amount: 1) high speed steel tool: vc=8 ~ 12 m/min. 2) Carbide tool: vc=15 ~ 60 m/min. 3) PCD, PCBN natural diamond tools: wet cutting vc=200 m/min: dry cutting vc=100 m/min, P 0.05mm, f 0.05mm/r, otherwise the higher The calculation formula is: ha=100- l/0.025

⑤ cutting fluid: emulsion and extreme pressure emulsion are used for one strand. Extreme pressure cutting oil is used for finishing

⑥ note: when turning slender shafts (rods), the movable center and nylon should be used as the claw support of the tool heel and center frame; When reaming, use 60% castor oil + 40% kerosene as cutting fluid; When tapping, appropriately increase the diameter of the bottom hole

5. Cutting of chilled cast iron:

the surface of this kind of cast iron is white cast, and the hardness can reach about HRC60; The unit cutting force K C can reach 3000mpa, which is 1.5 times that of cutting 45 steel; The cutting force is concentrated near the edge, and there are pores and sand inclusions in processing, which is easy to damage the tool during cutting; Its brittleness is large, and phenomena such as edge collapse and slag dropping will occur during cutting

① tool material: 1) cemented carbide: cemented carbide with high hardness and bending strength should be selected. YS2、YS8、YS10、600、610、726。 2) Ceramics: SG4, at6, SM, ft80, ft85. 3) PCBN: used for fine turning

② tool geometric parameters: 1. Obtain some words from the page content in advance during pretreatment) cemented carbide: 0=0 ~ -5, 0=5 ~ 10, R 45 (r=45), s =-5 ~ 10, =0.5 ~ 1 mm

③ cutting amount: 1) cemented carbide tool: rough machining vc=7 ~ 10m/min, p=5 ~ 10mm, f=0.5 ~ 1.5mm/r. Finishing: vc=15 ~ 20m/min, p=0.5 ~ 2mm, f=0.3 ~ o.5mm/r. 2) Ceramic cutter: vc=40 ~ 50m/min, p=0.5 ~ 2mm, f=0.3 ~ 0.6mm/r. 3) PCBN tool: vc=60 ~ 70m/min, p=0.5 ~ 2mm, f=0.1 ~ 0.3mm/r

6. Turning of thermal spraying (welding) materials:

thermal spraying materials are mostly multi-component high-strength alloys, which are sprayed onto the surface of the workpiece at high temperature and high speed, greatly improving the hardness, corrosion resistance, wear resistance and heat resistance of the surface of the workpiece, and are widely used. The hardness of copper based and iron-based powder coating is relatively easy to cut. The hardness of cobalt based and nickel based powder coating is HRC50, which is difficult to cut. The hardness of cobalt coated WC, nickel coated WC and nickel coated Al2O3 coating is HRC65, which is the most difficult to cut

① tool material:

1) cemented carbide: hardness hrc45, using YG, YW cemented carbide; Hardness: 600, 610, 726, 767, YD05, yc12, YS2, ys8; hardness: HRC65, YG3X, YD05, yc09, yc12, ys8, 600, 610

2) ceramic tool: pcbn

② tool geometric parameters: 0=0 ~ -5, 0=8 ~ 12, R 45

③ cutting amount: cemented carbide vc=6 ~ 40m/min; Ceramic cutter vc=18 ~ 80m/min; PCBN tool: vc=24 ~ 160m/min. p=0.15~0.6mm; f=0.1~1mm/r。

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