High speed machining of the most quenched steel 0

2022-08-08
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High speed machining of hardened steel

When Machining Hardened Steel with end mills, the increase of cutting depth and feed per tooth will cause a significant increase in cutting resistance. Therefore, under the condition of small cutting depth and no increase of feed per tooth, the high-speed milling method is extremely effective. However, with the increase of the hardness of the workpiece being processed, the cutting heat is also increasing, making the cutting edge of the tool in a high temperature state. In this way, the tool wear will be aggravated due to diffusion and oxidation. Therefore, the stability of tools used for high-speed milling hardened steel at high temperature is very important

this paper introduces the cutting examples of hardened steel. Cemented carbide end mills coated with a heat-resistant coating are used for cutting hardened steel. This heat-resistant coating has good oxidation resistance, wear resistance and other characteristics at high temperature. In addition, CBN end mills, which are attractive in the field of high-speed machining, are also used

examples of heat-resistant coating end milling cutter

in order to realize high-speed milling of hardened steel, in addition to the high bonding strength between the coating and the cutter, it is also essential to improve its hardness, heat resistance and oxidation resistance

the oxidation starting temperature of the heat-resistant coating (Wx super coating) being developed and put into use by OSG company has increased significantly from 800 ℃ in the past to 1300 ℃. Even under the high temperature reached by high-speed cutting hardened steel, the increase of oxidation temperature can effectively prevent coating damage, so as to prevent the cemented carbide matrix from grinding due to oxidation and diffusion. The compressive strength of Jinan assay carton class 1 is based on the deterioration of the corrugating paper base. Moreover, compared with the previous coating, the hardness of this coating is also improved, which can prevent the abrasive wear of the coating itself

next, the series of end mills with super heat-resistant coating and their processing examples are introduced. Process SKD11 (62Hrc) workpiece with Wx special ball end mill (wxs-ebd) (processing condition: use tool: wxs-ebd

r1 × 4; Workpiece material: SKD11 (62Hrc); Speed: 32000r/min; Feed speed: 2800mm/min (0.038mm/tooth); Cutting method: machining cavity; Cutting depth: α a=0.04mm,Pf=0.05mm; Cooling method: air cooling; Machining machine: vertical machining center (hsk-e32)). It can be seen from the processing results that compared with the previous coating, wxs-ebd has slower wear and can maintain the R shape of the ball end mill for a long time

an example of side milling SKD11 (60HRC) with Wx super heat-resistant square head multi edge end milling cutter (processing conditions: using cutter: WXS can be selected by yourself; -ems Ф 10; Workpiece material: SKD11 (62Hrc); Cutting speed: 150m/min (4800/min); Feed speed: 860mm/min (0.03mm/tooth); Cutting method: side cutting, undercut type; Cutting depth: α a=10mm, α r=0.5mm; Cooling method: air cooling; Machining machine: vertical machining center (BT40)). Despite the high cutting speed of 150m/min, the tool wear is still relatively stable, showing the effect of heat-resistant coating

the development of new coatings (Wx super coatings) has greatly improved the performance of carbide coated end mills in cutting hardened steel

cbn end mill machining example

cubic boron nitride (CBN) is second only to diamond in hardness and thermal conductivity, has little reaction with ferrous materials, and has better thermal and chemical stability than diamond. Therefore, it can be used to process iron group metals that are difficult to be processed by diamond

cbn is not a natural material, but synthesized by the same process as polycrystalline diamond under high temperature and high pressure. However, the type of binder and CBN concentration used in the synthesis can greatly affect the mechanical properties and heat resistance of CBN

cbn tools were mainly used to process cast iron when they were first introduced, and their use has gradually become popular. Recently, due to the micronization of CBN particles, the improvement of binder, especially the improvement of tool shape, even for the cutting of ordinary carbon steel and hardened steel, it also shows a good effect. The following is an example of CBN end mill cutting hardened steel

an example of machining the straight wall of hardened steel SKD11 (60HRC) with CBN end mills (processing conditions: using tools: ① cbn-cr-eds φ 10 (2 teeth) ② carbide coated end mills φ 10 (6 teeth); Workpiece material: SKD11 (60HRC); Cutting speed: ① 400m/min (12740/min); ②20m/min(640/min); Feed speed: ① 1270mm/min (0.05mm/tooth); ② 190mm/min (0.05mm/tooth); Overhang length: 50mm; Cutting depth: ① α r=0.5mm( α a=5mm × 8 times); ② α a=40mm, α r=0.01mm; Inclination: ① 2~6 μ m; ②10 μ Above M; Cooling method: air cooling; Machining machine: vertical machining center). A 40mm wide straight wall is machined with a short edge long neck end mill. High speed cutting is carried out with an axial cutting depth of every 5mm, and the inclination of the machined surface reaches 6 μ Below M. The wear of the end milling cutter after machining is very small, and it can continue cutting

machining example of CBN ball end mill series cbn-sxb with spiral edge. This kind of ball head spiral edge is conducive to the formation of thin chips and intermittent cutting effect. It is generally used for cemented carbide ball head end mills

although the cutting edge of CBN milling cutter is very difficult to grind, OSG company still adopts spiral edge as the basic edge shape, and has developed a ball end milling cutter that is particularly suitable for the geometry (negative angle) of CBN cutter, which has been put on the market. Due to the dual effect of this spiral edge and CBN special materials with good strength and toughness, cbn-sxb can adopt a larger cutting depth than CBN ball end mills in the past, and can realize stable cutting even when machining complex shapes with changing cutting loads

a cutting example of a simple model of metal mold for machining SKH51 (65hrc type IV sample is used to determine the Poisson's ratio of the above two kinds of FRP) with cbn-sxb (processing condition: tool used: cbn-sxb

r1 × 5; Workpiece material: SKH51 (65hrc); Spindle speed: 40000/min; Feed speed: 6000mm/min (0.075mm/t); Cutting depth: α a=0.03mm,Pf=0.05mm; Cooling method: MQL; Machining machine: vertical machining center). The tool path is not a straight line, but the mold cavity shape is processed at the local concave convex part. The state of the machined surface of the workpiece shows that, needless to say, in the initial stage of cutting, even after the cutting length reaches 70m, the cutting trace is still uniform and maintains a good cutting state

High Speed Machining Hardened Steel use the mouse to find out the data corresponding to each point on the experimental curve; High speed milling of hardened steel will produce a lot of cutting heat, in fact, most of the heat is transferred to the chip. Therefore, it is very important to remove the chips from the cutting area and the workpiece as soon as possible. However, if a large amount of water-soluble cutting fluid with cooling effect is used to remove chips, repeated intense heating and cooling in a short time will lead to thermal cracks and greatly shorten the tool life, so attention must be paid

in order to avoid this problem, the effect of blowing cooling is remarkable, especially micro lubrication (MQL) cutting is very good for improving the quality of the machined surface. MQL will not produce a sharp cooling effect that can induce heating cracks, because the coolant contains a small amount of oil, which improves the lubrication performance and helps the cutting edge enter the machined surface, so as to obtain good machining quality. Therefore, it can not only improve the roughness of the machined surface, but also improve the waviness and perpendicularity of the machined surface. More importantly, it can maintain the stability of tool life

it should be noted that the rotary vibration of the tool not only worsens the quality of the machined surface, but also shortens the service life of the tool. Especially when cutting hardened steel, small vibration is also easy to induce tool collapse. Therefore, the clamping method of cutting tools and workpieces becomes particularly important. The hot mounted tool holder has good dynamic balance performance, high clamping accuracy and large holding force, which can be said to be a very effective tool clamping method

the above introduces the cutting examples of hardened steel. It can be said that in the past, the field that could only rely on grinding and EDM can now be completely replaced by cutting

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