The damaged when interrupted cutting of hard alloy razor blade is analysed
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660.
0500.
11600B5.
3130.
300.
11300C8.
381540.
Method of 216002 cutting experiment and temperature measure result cutting experiment to be in lab of center of hard alloy factory undertakes individual plant continent. Experiment method is in rectangle of the turning on lathe sectional test specimen, with condition of imitate interrupted cutting. Test specimen material is contain 0.
6 ～ 0.
8%Mn, 0.
5%Ni, 0.
5%Cr and 0.
The carbon steel of 5%Mo (hardness is HV170) about. Use A, B, C3 to plant respectively the hard alloy cutting tool of the brand undertakes cutting, content of cutting tool composition sees a table 1. Angle of geometry of blade of cutting tool cutting: Horizontal forward horn and blade dip are 0 ° , transverse hind horn and deputy hind horn is 6 ° , beyond slant horn is 0 ° , deputy slant horn is 6 ° . Typical cutting condition: 95m/min of ＝ of cutting speed V, feed F=0.
25mm/r, cutting deepness Ap=6mm. Because be opposite cutting is sectional when the test specimen that is 50mm × 250mm undertakes cutting experiments, cutting tool of all brand hard alloy after using afore-mentioned cutting condition cutting two minutes all appear crackle, because this is its typical cutting condition certainly. Use cutting tool, the law measures workpiece thermocouple cutting tool, cut bits sectional temperature. Measure result model to record a curve to see a picture 1. Go out to be begged according to the change of curvilinear slope most pulmonary circulation temperature, need to photograph next record curves with oscillograph, go out according to magnifying the photograph is begged next most pulmonary circulation temperature. Graph 1 cutting tool, workpiece thermocouple model records a curve (underside of A) razor blade (coping of B) razor blade pursues when the 2 installation places that measure tepid couple are analysing mechanism of cutting tool damaged, need knows the temperature of cutting tool interior distributings. For this, thermocouple and thermal resistor are used to measure the interfacial temperature of bit in cutting process, can calculate according to bit interface temperature a temperature of cutting tool interior. The installation place that measures tepid couple sees a picture 2. The typical temperature that measures in bit cutting process sees a table respectively 2, watch 3. Be in every time in cutting experiment process, record the cutting strength of cutting tool continuously with ultraviolet recorder, with install the appearance of corrective meet an emergency on arbor to determine tangential force and feed force. The model that expresses 2 thermocouple measures an outcome (the C brand hard metal that uses alumina spacer) cutting time (position of Min) thermocouple installation and measure temperature position 1 position 2 positions 3 positions 4 positions 50.
45 ℃ of 585 ℃ 50 ℃ of 50 ℃ 195 ℃ of 40 ℃ 60 ℃ of 55 ℃ 50 ℃ of 60 ℃ 65 ℃ of 2115 ℃ 75 ℃ of 75 ℃ 3120 ℃ of 60 ℃ 65 ℃ of 75 ℃ express 80 ℃ of 75 ℃ the model of 3 thermocouple measures an outcome (use the C of steel spacer.
35 ℃ of 570 ℃ 40 ℃ of 40 ℃ 175 ℃ of 35 ℃ 45 ℃ of 45 ℃ 40 ℃ of 45 ℃ 50 ℃ of 285 ℃ 55 ℃ of 55 ℃ 390 ℃ of 40 ℃ 60 ℃ of 55 ℃ 50 ℃ of 60 ℃ the observation of 3 cutting tool damaged pursues cutting tool of department of 3 computation coordinate is undertaking, when its attaint configuration and successive cutting same, can divide face of the knife after be to wear away, crescent moon wears away depression, cutting tool is permanent be out of shape the mechanical burst that reachs cutting blade. Through having damaged observation to experiment cutting tool, face of the knife after the hard alloy cutting tool that discovers name of A, B arises very quickly wears away and crescent moon wears away depression, at the same time of the hard alloy cutting tool of all brands before knife face all produces transverse crackle (can be being regarded is hot crack) . Experiment discovery, once hard alloy cutting tool produced hot crack, can cause damaged very quickly, produce face of the knife before blade of cutting blade collapse is mixed to flake phenomenon. The computation of stress of flexibility of 4 razor blade adopts a plan 3 show coordinate is stress of flexibility of computational razor blade. The direction of cutting force and Z axis are parallel, the stretch equation of this direction is (1) assumes above all produced thermal stress, and when EZ=0 of meet an emergency condition of planar meet an emergency maintains go up in Xy plane. The stress that concerns with this condition is used cast order " " express, according to type (the join forces that 1) can seek a Z way is (2) is about the join forces quadrature of Y axis (3) is in type (2) , (in 3) , as a result of symmetrical cause, active force is done not have on Zx plane and Zy plane, because of equal Yu Ling of this the 2nd integral. When originallying to go up in arbor in view of knife reel already bore actually physical sanction, apparent: ① razor blade can random of edge Z direction is adjustable; ② razor blade can bend arbitrarily on Zx plane; ③ already was originallied by clip as a result of bit, because this cannot be in,Zy plane bends at will. So, the basis assumes condition of planar meet an emergency, by type (the stress of the generation when 1) begs the cutting blade thermal stress that go out to must add sanction to eliminate (4) basis type (2) , (3) , type (4) can simplify in be type: Tc -- the temperature that gets after Tr of cutting blade temperature is integral, calculate to use graphic form namely afore-mentioned integral, the temperature T that nods each on Xy plane can show temperature curve 4 times to beg according to the graph piece. For scale these curves, cutting tool, temperature of area of the contact that cut bits can press a plan along with the metabolic circumstance of time show a form 1 times to undertake simplifying. Specific means involves other thermodynamic knowledge, length of be confined to, be omitted here. * .
According to the temperature ○ that the experiment gets.
Conjectural temperature - .
The limits of bit conducts heat coefficient H=0.
5 stress are worth the temperature curve of plane of 30 graphs 4 Xy determine with the analysis as above, the thermal stress analysis that regards bit complete elastomer to undertake cannot show the way of edge cutting blade that can cause apparent crackle any pulling stress. Accordingly, need key analysis can be caused initiative the greatest stress that reduces metabolic to be brought about by temperature of peak value loop. If the graph shows the stretch model that should use C brand hard metal 1 times to measure the E=5 that decide a value,with cutting tool one workpiece thermocouple measures the cycle of a typical temperature that go out.
24 × 1011N/m2 and A=5 of linear expansion coefficient.
When ℃ of 2 × 10-6/ , criterion by type (4) begs a thermal stress to be worth Sx=2 7, 24, 800(-Te+Tr) is become cutting in the begining, bit temperature and environmental temperature are identical, tr=20 ℃ . If measure the peak value that gives this brand hard alloy 700 ℃ of ＝ of circular temperature Te, criterion Sx=-1.
852864 × 109N/m2. As cutting undertake, stress wear off, cutting reachs steady state after about 2 minutes, right now Te=200 ℃ , of generation the biggest press stress to be Sx=1.
3624 × 109N/m2. Pass temperature of set lowest loop (Te=350 ℃ ) , when can begging a refrigeration period to end through similar computation most pulmonary circulation stress. Beg the greatest stress that go out to appear to still can't make C brand hard alloy produces plasticity to be out of shape via computation (need about when 700 ℃ 2.
Of 7428 × 109N/m2 succumb press stress) . Outside dividing thermal stress, return the influence that should estimate cutting pressure. To offer 2.
The unit cutting force of 484 × 109N/m2, to typical cutting condition (feed F=0.
25mm/r, cutting deepness Ap=6mm) , what the requirement measures is tangential cutting component of force amounts to 3920N. The average pressure that action is cutting bits interface to go up is likely slightly under unit cutting force. According to estimation, be located in cutting blade around before the pressure on knife face is an unit about tangential the 2/3 of cutting component of force, namely Sy=-1.
656 × 109N/m2. To the condition of meet an emergency of Xy plane, zero hour is equal to in the stress of X direction, the stress on Z direction is type in, take U=0.
3. The place before be like is narrated, join forces should be not had on bit (or join forces quadrature) when, the quantity is in this planar meet an emergency to go up somehow can reduce. Should press 0.
When the fold of 83 has consideration, because be put in the conglutinate that cut bits, additional stress of remain still achieves Sx=-4.
14 × 109N/m2. Like the stress on direction of Y, Z the value appears the deviation of certain level, plus thermal stress, criterion stress cost can arrive high enough causes rate of metabolic of cutting tool plasticity. 6 razor blade are out of shape the analysis analyses bit to compress metabolic now likelihood means. Inspect bit above all by face of cutting blade support or oppose of a paragraph of outspread area be out of shape. Although the add and perpendicular stress of because of cutting bits conglutinate generation meets those who quicken this area be out of shape, but this kind is out of shape may not can extend whole area inside, does its reason have at 2 o'clock: ? of joyous saliva of deceive of overstep one's authority returns of that Xing Bei to denounce school take along sth to sb to closely question dew of go whoring of plating rice huller still plans travel goes straight towards deceive of of plating of horsefly of Pi know well Si of Ge of of Xu of Xing of Connors another name for Jiangxi Province throws go whoring of rice huller of impaludism of widow of α Ρ laying feng4huang2 dew admits. Because these crackle begin at standing by cutting blade slightly hind, this makes clear compress be out of shape blade of cutting be been in by limitation is hind of a stricture before on knife face. The basis has data, this one narrow area is bearing to press stress Sy and Sz, in cutting process of the loop, both numerical value is about 1.
38 × 109N/m2 or taller. When cutting temperature achieves 700 ℃ , press stress Sy and Sz to bring about hard alloy razor blade to produce slight plasticity to be out of shape likely. But should point out, determine the temperature that the thermocouple when stress is worth indicates is the average temperature on face of the conglutinate that cut bits apparent, in be apart from the local temperature inside the highest temperature area with cutting very close blade to want to be gotten high much (exceed 900 ℃ ) about. If this kind of possibility exists really, local thermal stress, sz will increase, at the same time the compressive strength of hard alloy can be reduced (have about 2 only.
07 × 109N/m2) . Here the condition falls, in the razor blade in cutting process of the loop complete likelihood produces local compression model J sex is out of shape. As before knife face cools lowermost temperature, can arise pull stress. Usually, need about 1.
Of 38 × 109N/m2 pull stress to just may cause bit to rupture, but below the circumstance that circulates for many times in stress, pull stress inferiorly to cause bit to rupture with respect to enough. To study this one issue, need has the accurate data of the mechanical sensitivity that leaves material correspondence force in high temperature condition. The hard alloy razor blade that 7 conclusion holiday does not have initiative stress like suffers thermal strain place to control with the means of complete elastomer, calculate the result makes clear, in cutting any phase of process of one cooling loop all won't arise pull stress. The bit of brand of 3 kinds of hard alloy that this one conclusion has cutting experiments to using alumina spacer and steel spacer respectively holds water, but can conclude, what use spacer type not to have practical effect to this. Through cutting the experiment discovers, in cutting process, the mechanical bear of thermal stress and cutting tool exists at the same time, the compression that causes cutting tool likely thereby plasticity meet an emergency. This kind of plasticity is out of shape the likelihood happens in cutting tool the position with the top temperature in all bits contact areas, and inside the some limits that this place is located in cutting blade the reverse side. Mean existence to pull stress in view of the generation of crackle, can figuring these pull stress accordingly is the cooling phase that circulates in cutting by outside flexibility the object is out of shape to plasticity the area brings to bear on active force place causes. Conclusion of this one analysis but according to crackle initiative at cutting blade the reverse side the fact of some limits gets test and verify. According to observation result, the damaged form of cutting tool has two kinds: Blade of collapse of ① cutting blade; ② uprights between two crackle before knife range occurs local flake. In interrupted cutting process, the reason of blade of collapse of cutting tool happening still very not clear, but likelihood and thermal stress do not have a relation, because also can produce collapse blade phenomenon when low speed cutting. But, the edge is perpendicular the crackle that arises at cutting blade direction may concern material of 2 pottery and porcelain to be able to produce hot burst with thermal stress is well-known fact, but exist as a result of the crackle crisscross of all sorts of types, because this hot crack is not the immediate cause of damaged of cutting tool of pottery and porcelain it seems that. However to hard alloy cutting tool, at the knife before that part between two crackle when interpose face happening flakes when, hot crack often can cause cutting tool damaged directly. With cutting tool, the discovery when workpiece thermocouple measures temperature, in circular cutting process, the biggest and most pulmonary circulation temperature keeps changeless, and the effect that does not suffer place to use spacer type. Accordingly, in the compression of the generation in cutting process thermal stress value can pass the volume-temperature of bit to try to control. Undertake to hard alloy cutting tool before cutting begins warm-up processing can be reduced taller initiative press stress, be helpful for raising the performance characteristics of cutting tool thereby. CNC Milling