Group get all sorts of getting model (8)

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The 20th control that cut bits and break bits to be in bore process, the pilot that cut bits is important the task is to want to assure to discharge bits smoothly. Bore is a kind half enclosed cutting, cut bits to cannot resemble turning free in that way eduction. When should cutting bits to be squeezed in the platoon in aperture not to come out, cutting fluid is flowed into not easily also, make auger cut temperature heighten, auger cut force to increase, aggravate broach wears away, serious when cause broach to break off or burn dead. Accordingly, the problem that discharge bits becomes a key sometimes, get deep Kong Shi especially, people often wants halfway a few times to exit broach to have bit, execute " woodpecker type " classification feed, this not only the influence manufactures efficiency, and cause easily cut bits the case that gets blade to be squeezed bad. Want to discharge bits smoothly, basically should reduce as far as possible cut bits to be in put apart process with the attrition obstruction between hole wall, broach, and this and the geometrical appearance of the type that cut bits, broach and cut bits getting the direction that pours out of on blade to wait about. Cut bits too finely, go against a bits; Cut bits ceaseless, twine go up in broach (in the bore on drilling machine) , also increase the resistance that discharge bits. Visible, the issue that discharge bits looks from bore process, with cent bits, roll bits and break bits 3 respects close tie, cut the size of bits, curly appearance, length that cuts bits namely, what affect a bits directly is successful. One, the classification that gets bit and the classification that its form a condition to cut bits mediumly about metallic cutting, people already had many jobs, offerred the program of a variety of classification, be like center of information of Germany metal cutting (INFOS) 10 kinds of taxonomy; Japanese essence machine learns 9 model taxonomy, and the classified plan of CIRP. But basically be a basis among them turning circumstance. In view of the characteristic in bore, here is mainer the real case that presses twist drill bore yes, summary is Baconian the song sort of bits of one run the drilling tool into the well, if express 5-20 place,show. Bore interrupts bits often appearing transfer model the implementation when cutting bits. Not only banding bits constant in order to transfer model implementation breaks bits, and snail coils short bits also is belonged to actually transfer model. The variation that people can use this kind of type that cut bits and transfer will achieve reasonable the aim that stops bits. Additional, to cutting the requirement of bits and stand or fall, with treatment closely related means of method, cutting. The stand or fall of bits appearance is cut in what what in expressing 5-20, comment, just basically be aimed at what use word of from time to time of twist drill bore on drilling machine (broach rotates) . 2, the requirement to cutting bits as above, set out from the actual condition of twist drill bore, to cutting the demand of bits appearance and length, be different from turning already, also be different from undertake deep Kong Zuan cut with deep Kong Zuan. To latter, bits deep aperture is discharged to get outside Chan Ren no matter (the gun is gotten) or inside platoon bits deep Kong Zuan (like) of BTA deep Kong Zuan, all used the cutting liquid of constant pressure and larger flow, can assist the eduction that cuts bits, and twist drill all is nature to discharge bits commonly. Assess cuts a of bits character important parameter, to cut ω of bits cubage coefficient. Coefficient of the cubage that cut bits is to cut bits sky to accumulate what excise material bulk with place to compare. ω =V η / in V ω type: V ω -- the metal excises a quantity, be ask when it is certain to be in inside the primitive bulk of excises workpiece material; V η -- this share data turns into after cutting bits, the nature that cut bits piles the bulk that get together. Obvious, ω of coefficient of the cubage that cut bits goes to those who cut bits to be occupied in working ground place to deposit a space except the influence outside, affect the successful rate of a bits and sex of safety in operation especially. According to statistical data, the bits with broken collapse (include acicular bits) , 2 ～ of ω ＝ 4; Rupture unit bits (include) of bits of small C form, 5 ～ of ω ＝ 6; Cockle unit bit, 8 ～ of ω ＝ 9; Send strip bits, 10 ～ of ω ＝ 15; Half cricoid bits (include big C form bits and banding short bits) , 15 ～ of ω ＝ 30; Snail coils short bits (include) of pagoda shape bits, 30 ～ of ω ＝ 50; Snail coils long bits, 50 ～ of ω ＝ 100; Banding come loose in disorder bits, 100 ～ of ω ＝ 300; Banding straight long bits, 300 ～ of ω ＝ 400. Normally, to inside when platoon bits deep aperture gets have the aid of to discharge bits at cutting fluid, because platoon bits passageway is small, do not jam to assure to cut bits, <10 of general requirement ω . And to twist drill, ω is too small not appropriate, 30 limits compare 15 ～ of ＝ of general requirement ω appropriate, namely with banding short bits, snail coils short bit is better. Cut bits length normally in order to be between hole depth length and length of broach job section relatively appropriate. Accordingly, the requirement that uses twist drill drill is reasonable break bits, cut bits not to answer namely too long also do not answer too broken. Cast-iron to getting kind brittleness material, produce broken end bit commonly, go against a bits. Right now, answer to control angle of blade form, cutting tool and cutting dosage as far as possible, make its are formed " false " banding bits. 3, reasonable the measure that breaks bits cuts bits to break or ceaseless prime cause, forming a process to be out of shape mediumly at cutting bits with stress. This kind is out of shape and stress strive makes cut bits to rupture, but the itself that cut bits has a kind to fight ability again, should be out of shape (stress) exceeded those who cut bits to rupture the limit, perhaps cut bits to be out of shape motion changes ceaselessly, be in very flabby when deciding position, cut bits to be able to break off. Accordingly, when wanting to urge the end that cuts bits to achieve bit, should go from the both sides of the problem proceed with, namely: The first, increase cut bits to be mixed when form when discharging bits be out of shape and stress. The 2nd, reduce those who cut bits to rupture the limit. (One) increase cut bits to be out of shape (or stress) the total deformation that measure cuts bits and stress are comprised by two respects, it is to cut bits blade to excise it from workpiece on one hand when coming down be out of shape basically, or cry inside be out of shape; On the other hand, it is chamfer of helix of the edge that cut bits and hole wall when outward eduction, get the attrition of groovy surface and hole wall and collision, make its generation add be out of shape, or outside crying, be out of shape. Accordingly, want to increase those who cut bits to be out of shape, answer to begin from this two respects namely. 1.

Add basic metabolic measure: (If graph 5-34a place is shown,the blade outside 1) general gives edge with oilstone Bei; Or wear a face that break bits with emery wheel, if graph 5-34b place is shown, the horn before be being reduced a bit, make according to breaking the need of bits 10 ～ of γ Nc ≈ 15 ° , width B γ 1 approximate feed. Horn is reduced before, cut bits to be out of shape increase. (2) increases feed, make F ≥ 0.

3 ～ 0.

5 millimeter / turn, cut bits thickening so, cut bits to be out of shape increase. (3) reduces rotate speed appropriately. Because, when cutting bits to come down in excision, grain interior happens be out of shape, displacement, need proper time, accordingly, rotate speed can make slow cut bits to be out of shape more sufficient. Experience makes clear, those who use 20 millimeter of diametical D ≤ is basic model group get general carbon steel and steel of common alloy structure, use above these 3 kinds of measure cooperate each other, in bore feed F by small increase gradually, can get comparative the satisfactory result that break bits. Often see a paragraph a paragraph cut bits " , ... " from Kong Zhongshun interest jumps out, its length is equivalent to the working section length of broach about, this kind cuts bits most ideal. 2.

Add add metabolic measure: (Grind on 1) outer blade go out (roll) bits stage, if pursue,5-35 place is shown. Cut bits to come up against the rank stage on chamfer of this kind of helix from be poured out of on point, hold back it to glide, generation is add be out of shape, break off when reaching certain and curly level. Go up in general steel products with this kind of method bore, break bits very reliable, use at older bit to get the alloy structure steel with plasticity, taller tenacity (like 20CrMnTi) , the performance that break bits is better also. Bit is older, the 1/c of ratio B γ of 1 as deep as the stage C is γ of stage wide B about 4 ～ 10; Stage deep C is the 1/5 ～ 1/7 of first flank width about, must not exceed the frontal in part of first flank width greatly most. When feed F is proper, break bits very successful. Because break bits good, cut bits to be not blocked up not crowded, attrition is reduced, auger cut force to increase not much, if express 5-21. If B γ 1/c is too small, namely the stage is too late, can make cut bits too broken, cause collapse blade, reduce broach durability, make cut bits to be out of shape increase more. From here, should cause us to notice, no matter the sort of addition method of the metabolic that cut bits, raising cutting negative charge at the same time, produced new contradiction again then. Accordingly, we cannot to break bits increase desperately cut bits to be out of shape, should be handled appropriately however according to specific data, particular case. (2) is before broach on grind a semicircle hole to break bits chamfer, if graph 5-36 place is shown, in the horn before be being reduced appropriately (5 ° of γ Nc ≈ ) while, abrade give semicircle pit, basically use at getting alloy structure steel, its defect is blade is ground give or take a lot of trouble, broach is expended when be being ground again more. (3) is proper sharp angle of the blade outside increasing 2 Φ . Control cuts bits to pour out of direction, make cut bits ceaseless sprain adds in the generation on broach helix chamfer be out of shape. In the meantime, because sharp angle increases, increased C of α of the ply that cut bits (F/2sin Φ of α C ＝ ) , increased thereby cut bits to be out of shape, because this also conduces to,break bits. (4) is driven by drilling machine main shaft cut bits to rotate the centrifugal force of generation, also can increase the stress that cuts bits, will cut bits to be swung. (5) blade is ground piece T of λ of dip of end panel blade, consult this chapter gets group of the copper that do not have oxygen the 10th times. (When 6) broach design is made, in the end root part of blade valve the setting breaks bits rank stage or arris surface, consult the 3rd chapter the 4th. (2) reduce cut bits to rupture the fights ability and workpiece material function that ultimate measure cuts bits (basically be plasticity) reach closely related the figure that cuts bits. Improve the character breaking bits of workpiece material, can fall in permission condition on one hand, pass proper heat treatment, make the plasticity of material, tenacity is reduced, facilitate bits. On the other hand, do not answer in bore medium speed too tall, want to notice to cool adequately, prevent to because temperature is exorbitant,cut bits, and molten changes pliable but strong. Experience still makes clear, the appearance that cut bits also affects bits situation. (1) snail coils form -- common twist drill cuts this kind to cut bits commonly. Become when feed is not big, the Bao Erkuan that cut bits, like bedspring of a helix, become soft and pliable but strong, the obstruction that discharge bits cannot transfer department of the root that cut bits, break bits not easily. But feed is enough big when, because ω of its cubage coefficient is bigger, get of root of blade valve end and hole wall hold back, can make its break bits. But the circumstance that discharge bits still insufficient ideal. (2) sector -- group because grind,get gave slot of crescent moon form, of part of circular arc blade cut bits, become short sector bits to coil eduction. Because blade of this part cutting looks from two direction,this is, camber (consult the 3rd Zhang Hetu 4-7) , look from front view namely, point is form of crescent moon circular arc, change of T of λ of dip of end panel blade is very big also, the direction that this causes each a little bit to cut bits to pour out of is abhorrent, cut bits to present complex curly case, be helpful for breaking bits. (3) is narrow a form -- outside this kind is cut to cut bits after blade grinds chamfer of bits giving cent, break not easily commonly. But become when feed is bigger, the ply that cut bits increases, plus the certain measure that break bits, accordingly, can achieve commonly reasonable the requirement that breaks bits. Additional, still have a kind of special cutting kind of late -- motivation breaks bits law. Its principle is to use the feed in bore to change ceaselessly, cause those who cut bits to fashion a process is not stable, and deformation or rupture ultimate change will achieve bit. This kind of method perhaps calls pulsatile bore the law. Implementation feed orgnaization or the means with pulsatile and oscillatory workpiece, can be machinery (be like gimbal roll cam mechanism) , of ultrasonic or electromagnetic, detailed sees the 2nd order the 7th. (3) makings of a pithy formula that break bits is soft, stick, it is difficult that pliable but strong breaks bits, cutting bits to be out of shape is crucial. Sharp angle the largish, stage that break bits, pour the arris, round chamfer, face that break bits, turn speed, slow, refrigeration is sufficient, bits of suit the remedy to the case is broken easily. CNC Milling