The grinding characteristic of PCD and blade of PCD cutting tool grind a technology

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1 foreword develops as the high speed of modern science and technology, you Jujing diamond (PCD) , get together nitrogen of brilliant cubic metre changes boron (PCBN) etc the cutting tool variety that exceeds hard data to be made is richer and richer, its function also gets develop ceaselessly and rising. Diameter of bit abrasive bead arrives from tens of micron, a few micron accept rice class; Diamond, cubic nitrogen changes boracic content cent to be low content, medium content and high content; Bond has already metal, metalloid also have mixture stuff; PCD layer ply arrives from millimeter class micron class; The combinative means of PCD layer and hard alloy underlay has planar, moire side; PCD layer has the different character such as tall wear-resisting, tall tenacity, tall heat-resisting. At present the applied limits of cutting tool of PCD, PCBN enlarges aviation of car, spaceflight, accurate machinery, home appliance, lumber, electron electric wait for an industry, use at making knife of lathe tool, boring cutter, milling cutter and broach, reamer, Huo, curium knife, engrave knife, razor. Although cutting tool of PCD, PCBN develops such fast, but because its are tall,the cutting tool blade that hardness brings about grinds difficulty to perplexing most user all the time, of bit grind again also basically be finished by manufacturer of production of primary cutting tool. Not only cutting tool price is high, date of delivery is long, and take up company circulating fund. Accordingly, very the blade of the grinding characteristic that is necessary to study PCD seriously and PCD cutting tool grinds a technology. The manufacturing technological process of the cutting tool of workmanship PCD cutting of 2PCD cutting tool includes polishing, cut, solid to receive commonly, blade is ground, qualitative check. PCD exceeds diameter of hard data semifinished product to have 1/2 normally, 1, 2, 3, 4 inches, its surface is general coarser (10 μ of Ra2 ～ M) , cannot use at making cutting tool directly, need to make via abrade polish its surface reachs lens range (Ra ≤ 0.

01 μ M) , become certain geometry appearance and the bit that dimension asks through Laser Cutting or treatment of cut of electric spark line next, go further pair of razor blade and matrix wait for solid to receive a face to undertake machinery and chemical processing, use solder of silver radical hard drill steel to accept bit firm next go up at matrix, blade of emery wheel of final classics diamond is ground. PCD cutting cutting tool makes the blade that one of technical keys are cutting blade grind quality. Material of head of high grade knife lacks ideal blade to grind craft and technology to will cause resource to waste, the blade that has used grinds craft to be able to promote the product of cutting tool quality, reduce cutting tool to use cost. The PCD of grinding treatment characteristic of 3PCD material is agglomeration falls in high temperature superhigh pressure with a few binder by the diamond of special processing and become. The diamond grain that arranges without foreword makes PCD is had even, extremely tall hardness and wearability. PCD can be used at nap of cutting cutting tool, emery wheel, geology to drill, measure measures a head, pull silk to feel, gush is arenaceous feel etc. But the tall hardness of PCD and tall wearability also brought very great difficulty to its treatment. The tall hardness that domestic and international scholar is aimed at PCD material and the treatment difficult problem that tall wearability brings had much research and test, include electric spark treatment, ultrasonic treatment, electrochemistry treatment, laser beam machining to wait among them, obtained certain result. But integration analysis discovery, these processing technique apply to the rough machining circumstance of PCD material more at present. Want to acquire quality of good PCD cutting point, optimal treatment method still is use grinding of diamond emery wheel or abrade. The grinding treatment of PCD basically is the result that two respects mix machinery and thermochemistry to use. Mechanical action is the diamond that wears bead to be formed to the ceaseless concussion of PCD material through diamond emery wheel is small broken, wear away, fall off or cleavage; Thermochemistry action is the high temperature that PCD of grinding of diamond emery wheel forms makes diamond produces oxidation or graphitization. The result of both mixture action causes PCD material by purify. Its grinding machines a characteristic to basically be: (1) grinding power is very great diamond is foregone and mineral in the material with highest hardness, the 1/50 ～ 1/800 that is hard alloy only with the wear extent that conjugate of all sorts of metals, metalloid material chafes; The hardness of PCD (HV) for 80 ～ 120KN/mm2, be next to single crystal diamond, outclass hard alloy. When using PCD of grinding of diamond emery wheel, initiative cutting intensity is very high, it is hard alloy about (0.

4MPa) 10 times above; Can amount to than grinding 1.

104 ～ of 2 × 1.

4 × 105J/mm3; Because of hard alloy of grinding of outclass of this grinding force. (2) grinding comparing is very small because the hardness of PCD and wearability are very tall (the 16 ～ that are hard alloy relative to wearability 199 times) , its grinding is compared when grinding PCD it is only 0.

005 ～ 0.

033, the 1/1000 ～ that is hard alloy about 1/100000; Grinding efficiency only 0.

4 ～ 4.

8mm3/min. Accordingly, to make sure the point quality of cutting cutting tool and purify are measured, grinding time efficiency of very long, treatment is very low. In addition, when the hardness of PCD, content, size is distinct, its grinding time also six to one. (3) granuality affects material of very big PCD to use at cutting cutting tool to basically divide by granuality it is 3 kinds: Thick granuality (50 μ of 20 ～ M) , in granuality (10 μ M is controlled) spend with granule (～ 5 μ M) , its grinding force, grinding is counted than differring to come severalfold decuple. Grinding of thick granuality PCD is compared highest, grinding is the most difficult also, and the point after grinding is dentate the most serious, quality is the poorest, but wearability is the strongest; Grinding of fine granuality PCD compares opposite lowest, grinding quality of the point after easier, grinding is best. The demand that blade of 4PCD cutting cutting tool worries pair of tool is based on afore-mentioned grinding characteristics of PCD, the demand that equipment worries to blade when machining PCD with grinding of diamond emery wheel is gotten higher than common tool grinding machine much. Basically have: (1) because PCD material hardness is very tall,the machine tool has good machining complex tigidity, because this grinder must have taller fight be out of shape ability, especially main shaft system and system of clip of cutting tool outfit. Force of the grinding when blade of PCD cutting cutting tool is ground amounts to 100 ～ 500N commonly. Because this asks,the axial tigidity of big, bearing and intensity want the axial way of the machine tool tall. (2) the machine tool has the journey to be able to mediate the short distance with adjustable rate places grinding of motive compose PCD to compare extremely low, the grinding treatment mechanism of PCD basically is to pass diamond what be pounded ceaselessly and form of material of PCD of arenaceous wheel pair is small broken, wear away, fall off, result of compound of action of thermochemistry of the mechanical action such as cleavage and oxidation, graphitization. Because this uses short distance to place motive compose to be helpful for improving grinding efficiency, improve quality of cutting tool point. Swing commonly be apart from 0 ～ 50mm, swing speed 20 ～ 60 / cent. (3) the knife clamping apparatus of the machine tool has high accuracy turn function and online detect device because PCD data is hard fragile and wear-resisting, its normally design of point of a knife is circular arc shape, in order to reduce the amplitude with cutting tool and relatively oscillatory workpiece. To realize the treatment of circular arc of point of a knife, the knife clip of the machine tool should have function of high accuracy circumgyrate and dimension of radius of circular arc of point of a knife and quality online detect device. Can avoid for many times to install the fixed position error that carry secretly comes to so, at the same time but twice improves treatment efficiency. The blade of cutting tool of 5PCD, PCBN grinds craft 5.

One of purposes that the blade of choice cutting cutting tool that 1 blade grinds craft grinds are to get sexual price to compare high cutting point quality, and the choice that the key of quality stand or fall wears emery wheel size in Yu Ren. Emery wheel granuality is finer, mouth of cutting blade collapse is smaller, and grinding efficiency is lower. For this but the precision according to blade of cutting tool cutting, utility (see a table 1) or its invalidation degree (see a table 2) , grinding work of blade of PCD cutting cutting tool art cent is thick, essence, fine 3 treatment phase. According to particular case formulate reasonable blade grinds craft to be able to improve treatment efficiency substantially. Express the 1 precision that presses cutting blade, utility to classify serial number, cutting blade precision, optional blade wears emery wheel size, utility A is thick, 0.

05mm, 230/270# ～ 320/400# , essence of rough machining B, 0.

02mm, M20 ～ M40, semifinishing machining C is fine, 0.

005mm, M5 ～ M10, finish machining is expressed 2 classify by edge invalidation degree (grind cutting tool again) serial number, invalidation degree, optional blade wears emery wheel size, remarks A is thick, cutting blade damaged 0.

5mm, 230/270# ～ 320/400# , or report processes B fine, mouth of cutting blade collapse 0.

3mm, M20 ～ M40 C is fine, cutting blade wears away 0.

1mm, rough machining of M5 ～ M10 is not tall to point requirement, optional report is machined or grinding is machined. Electric treatment efficiency is tall, appropriate is used at machining complex cutting tool, like printed circuit board use with floor of wood of aggrandizement of broach, cutting shape milling cutter. When grinding is machined emery wheel of optional thick granuality, the interface when blade is ground accumulates power of big, grinding tall (300 ～ 400N) , but the mental allowance with fast redundant purify; Fine granuality emery wheel is chosen when fine treatment, the interface when blade is ground accumulates power of small, grinding low (100 ～ 200N) , grinding hair quantity of heat is little, but material purify rate is low. This phase basically is to pass abrade with polishing, improve cutting point quality further. Finish machining is on both in. 5.

2 blade grind craft point (1) main shaft precision is close friends, end panel of general emery wheel is jumpy should ≤ 0.

02mm. Emery wheel end panel has beaten big, the emery wheel when grinding is intermittent concussion cutting blade, make cutting blade produces collapse mouth easily, obtain blade of high accuracy cutting hard. (2) emery wheel should have good dynamic balancing. Of emery wheel lopsided the vibration that will bring about a machine tool, affect precision of the treatment that be mixed by the point quality of treatment cutting tool then. (3) blade grinds emery wheel to answer preferential choose emery wheel of diamond of bond of pottery and porcelain. Because be in grinding process bond of pottery and porcelain is easy happen small crack make grind bead to get updating from acute, make grinding process smooth, be helpful for improving the precision that machines the surface and efficiency; Take second place is optional the emery wheel of colophony bond diamond with taller hear resistance. (4) timely attention emery wheel edge, and edge oilstone granuality wants appropriate. When machining PCD cutting tool with diamond emery wheel, emery wheel can happen jam, wear away passivation, high quickly blandly, bring about treatment speed to reduce the generation of He Zhenwen, noise, burn. Normally the choice uses emery wheel size than place fine 2 soft carborundum oilstone regards 1 ～ as edge oilstone. (5) because diamond fastens alloy happening easily with iron,chemistry diffuses, quicken emery wheel to wear away, because this answers,avoid as far as possible at the same time grinding metal and PCD. (6) circumgyrate of face of the knife after direction of emery wheel circumgyrate is sure to face from the knife before cutting tool. From blade of cutting of cutting tool of the PCD when grinding get power knowable, when circumgyrate of face of the knife after emery wheel is faced from the knife before cutting tool, its grinding force (tangential with the law Xiang Lizhi is mixed) action at cutting blade inward, namely stress of cutting tool press press, knife of not easy collapse; It is conversely pull stress, mouth of cutting blade easy collapse. When if written guarantee because of cutting tool compose reason must invert,blade is ground, choose metal of excel of colophony bond emery wheel and emery wheel of bond of pottery and porcelain. (7) grind efficiency to make sure cutting blade quality raises sword at the same time, but cutting tool hind horny cent is big hind horn and small hind horn. Grind first with thick granuality emery wheel big hind horn, because of muscularity of interface big grinding, blade grinds efficiency tall; Grind with blade of fine granuality emery wheel next small hind horn, will small hind control of first flank width is in 0.

1 ～ 0.

3mm left and right sides, it is good that interface small blade grinds quality. (8) the treatment that completes blade of pair of cutting tool cutting in holding clip as far as possible. (9) PCD blade grinds cooling fluid to should actor or actress choose fluid of water radical grinding. As a result of PCD material hardness Gaojunai heats up a gender to differ, excel of effect of refrigeration of fluid of water radical grinding is oily base grinding fluid, can improve treatment efficiency and point quality. Additionally the refrigeration in grinding process wants sufficient, cannot break stream, because small or grinding fluid quantity is intermittent,avoid supply causes diamond (emery wheel, cutting tool) a large number of using up (oxidation, graphitization) the point damaged with cutting tool. CNC Milling CNC Machining