The experiment of rule of change of trends of temperature of the cutting in milling of aluminium alloy high speed studies

The core viewpoint of theory of temperature of Dr. Salomon concerned cutting is: To given workpiece material, have value of rate of a critical cutting, when cutting speed exceeds this critical rate value, cutting temperature drops along with the accretion of cutting speed, cutting tool wears away to drop subsequently; And before reaching this critical rate value, as the addition of cutting speed, cutting temperature and cutting tool wear away to all rise gradually. Press this theory, existence of cutting tool life " dead cereal " , if cutting speed is crossed " to death cereal " , cutting tool life will increase significantly. The concerned research of other learned man also makes clear, increase as the abidance of cutting speed, of cutting temperature increase rate to drop, tend finally stable. The mechanism that can improve cutting tool life to high speed cutting has two kinds of explanations at present, after one kind thinks workpiece material enters cutting area, cutting high temperature makes its intensity, hardness is reduced, material bate, and cutting tool material is had relative to higher intensity and hardness; Another kind of theory thinks, as the addition of cutting speed, cutting area material cuts horn to increase, cutting is out of shape coefficient is reduced, material has not enough time to be out of shape below high speed, cutting tool and cut the coefficient of friction between bits to reduce, the quantity of heat of actual generation in cutting process decreases, and most quantity of heat by cut bits to take away, the quantity of heat that enters cutting tool is opposite less, make cutting tool durability rises thereby. This shows, the metabolic rule of cutting temperature is the serious side that reflects essence of process of high speed cutting. At present each country scholar had a large number of research to mechanism of high speed cutting, but the research that the critical rate that lowers along with the accretion of cutting speed to cutting temperature is worth reports up to now not much. Rule of dynamic to temperature of the cutting in milling of aluminium alloy high speed change had the article experiment research, aim to be library of technical data of high speed cutting build provide theory and experiment basis. 2 experiments principle and plan 2.

This experiment uses 1 experiment principle infra-red heat determines like appearance cutting temperature, its job principle is to be based on this Difen Boerciman is mensurable, namely the E in E=esT4(W/m²) type -- exterior radiate leads object radiate unit (depend on object surface property) S -- this Difen Boerciman is invariable, s=5.

67 × 10-10T -- the exterior temperature of radiation unit (K)E -- the radiation energy that the radiant energy of area of radiation unit unit measures infra-red heat to resemble appearance is received through infra-red detector and measuring object radiate unit, if the exterior radiate rate of radiation unit is foregone, can pass this Difen Boerciman is mensurable the exterior temperature that seeks a radiation unit. Infra-red heat passes orgnaization of smooth machine scanning like appearance the radiation energy of unit of radiate of ordinal exploration object, measure the radiant energy of every radiate unit ordinal changeover to be electronic video signal, through undertaking handling to this signal, come out with seeing the form of image show. The 2 dimension radiant energy that indication heat represented object appearance like the graph is measured, at the same time the temperature of corresponding also object surface distributings. Infra-red into measure lukewarm law to have like appearance intuitionistic, handy, remote blame contact is monitored wait for an advantage, and reach the exterior temperature of mobile to harsh environment measure measure to have great advantage. 2.

2 tests program is shown 1 times like the graph, establish inside of thin wall of the Zhou Xi inside the chamfer that milling cutter been machininging beforehand, the temperature field that uses infra-red heat to measure workpiece surface like appearance on the flank outside Bao Bi distributings circumstance. The temperature value that the flank outside the Bao Bi that measures nods each although the actual cutting temperature that under area of inside face cutting correspondence nods, namely lag of time of existence of process of change of temperature of flank of inside and outside, but document points out, beg algorithm instead through passing heat, the measurement that can resemble appearance according to infra-red heat the result is accurate get area of milling process cutting to nod temperature value each. Visible, of this experiment surveying lukewarm plan is feasible, the law of cutting temperature change that the rule of exterior temperature change that can measure like appearance according to infra-red heat studies high speed milling is medium. Test plan is as follows: (1) cutting cutting tool: Contain hard metal two blade establish milling cutter, diametical F30mm, use Gan Shishun mill; Cutting dosage: Milling width Ae=15mm, milling deepness Ap=1.

5mm, af=0 of every tine feed.

05mm. (Rotate speed of 2) main shaft chooses N=2500 respectively, 5000, 7500, 10000, 12500, 15000r/min in all 6 archives, the value of workpiece surface temperature to be being measured below different rotate speed undertakes comparative. (3) basis the geometrical appearance of workpiece, choose 30mm of × of 6 paragraphs of sectional 380mm to measure unit as a rotate speed, machine the groove that gives wide 60mm, deep 18mm first on outspread direction, thin wall ply is 3mm. (A few when the dot is using different rotate speed to machine opposite temperature that 4) has delegate sense to mirror workpiece to go up mainly are worth, measuring the) when place of end face 6mm is apart from to choose cutting tool of one reference point Q(to be opposite on cover central line, measure a workpiece same wall is large when different cutting speed reference point Q reachs his to be apart from cutting tool lead and 30mm of lag reference point locally P dot and the temperature value that R nods, so that reach,already machined the surface and photograph of work surface temperature the metabolic rule to cutting speed. The watch measures bit of temperature to be worth D=0.

3mm, milling deepness Ap=1.

Temperature of Vf(mm/min) of speed of feed of V(m/min) of speed of cutting of N(r/min) of 5mm rotate speed (° C) P needs time to Q place (S)t=30mm/Vf P drops relative to Q temperature rate (° C/s)P is nodded (+ 30mm) Q is nodded (reference point) R is nodded (- 30mm)2500 235.

5 250 52.

7 97.

6 46.

3 7.

2 6.

245000 471.

0 500 58.

2 116.

3 41.

5 3.

6 16.

147500 706.

5 750 62.

5 130.

5 35.

0 2.

4 28.

3310000 942.

0 1000 56.

8 117.

3 31.

3 1.

8 33.

6112500 1177.

5 1250 52.

1 102.

6 30.

1 1.

44 35.

0715000 1413.

0 1500 51.

0 100.

8 29.

6 1.

2 41.

5(5) cutting tool is decided by rotate speed with Vf(of some feed speed) from workpiece A end begins cutting, until from workpiece B end exits cutting, in whole cutting process, monitor like appearance with infra-red heat and record the heat that measures a range to distributing like temperature graph. 3 tests result and analysis 3.

Basis of 1 test result afore-mentioned test program, undertake like appearance with infra-red heat cutting temperature checks, if what right watch shows,check a result. Data of basis right watch but the metabolic relation curve between the main shaft rotate speed that if the graph is shown 2 times,draw gives and workpiece surface temperature and the main shaft rotate speed that if pursue,show 3 times and P dot nod temperature to drop relative to Q the relation curve between rate. 3.

2 data are analysed (1) by the graph 2 can see, the temperature change course that the Q that is opposite with cutting area cutting tool chooses is put in 2 effect, become namely N=7500r/min(namely cutting speed V=706.

When 5m/min) , q dot temperature is highest, when cutting speed continues to increase, q nods temperature to drop, tend finally stable. The article says V=706.

5m/min is the critical cutting speed when milling of aluminium alloy high speed, when cutting speed should is worth more than, cutting temperature begins to drop. (The metabolic pattern that the exterior temperature that the P that 30mm of dot of 2) lag Q is in nods follows cutting rate and Q drop are consistent, this proves to effect exists 2 times really when high speed cutting. In addition, from the graph 2 curves can see, the temperature span that P nods is less than Q dot, because P nods lag Q to nod 30mm(to be when N=7500r/min,this is, be equivalent to lag 2.

4s) , one part quantity of heat of the surface already was passed all round in medium. (The metabolic pattern that the exterior temperature that the R that 30mm of dot of 3) lead Q is in nods follows cutting rate and P, Q differred somewhat at 2 o'clock. When cutting speed is inferior, wait for cutting to nod R to nod exterior temperature taller; As the addition of cutting speed, r nods temperature to drop quickly; Exceed N=7500r/min(when main shaft rotate speed namely cutting speed V=706.

The temperature when 5m/min) drops rate reduce; When cutting rate increases further, temperature value tends stable. Because main shaft rotate speed increases,this is when, to assure constant every tine feed, must accelerate feed rate accordingly, the quantity of heat that brings about cutting area generation thereby has not enough time to workpiece wait for treatment area to deliver, quantity of heat basically by cut bits to take away, workpiece work surface is in cold conditions basically. (4) by 3 visible, as cutting speed rise, the temperature that already machined exterior P dot to be nodded at Q relatively drops on average rate increases. The article thinks, in maintain the cutting condition with every tine same feed to fall, as main shaft rotate speed and feed speed rise, heat source is accelerated in the floating rate of workpiece inside face, the quantity of heat that passes into workpiece surface when cutting way is same consequently decreases apparently, bring about workpiece to hold heat little, consequently temperature drops faster, make already machined exterior temperature to tend very quickly stable. Visible, great majority of heat in metal cutting by cut bits to take away, this is the main reason with lesser temperature rise of the workpiece in treatment of high speed cutting. Lesser workpiece temperature rise is helpful for winning favorable treatment exterior integrality and because workpiece is hot,restrain effectively be out of shape and bring about treatment precision to lose. This shows, high speed cutting machines material thin wall hard to the aviation of thermal conductivity extreme difference treatment is very favorable. The research of document makes clear as a result, in high speed cutting, interrupted cutting and successive cutting photograph are compared, in identical cutting distance, cutting tool durability will rise substantially. Use in article experiment establish mill to attribute interrupted cutting kind, every tooth should be endured in cutting heat repeatedly and cooling process, cutting tool temperature won't increase continuously, present the regularity that warm up and drops in temperature to change inside certain limits however, this raises those who be helpful for cutting tool life. About the material change rule of cutting tool temperature, still be in further research. 4 conclusion (1) falls in the circumstance with cutting inferior speed, cutting temperature follows the addition of rotate speed and lift, but achieve some after critical cutting speed is worth, continue to increase as rotate speed, cutting temperature drops instead. When aluminium alloy of high speed milling, critical cutting speed is 706.

5m/min. (2) is closer to leaving cutting area already machined the surface (if P nods) , as the addition of main shaft rotate speed, temperature drops rate increases, the heat in metal cutting when high speed cutting mostly by cut bits to take away. To work surface, the workpiece temperature that nears cutting area (if R is nodded) drab along with the addition of cutting speed drop, after cutting speed crosses critical value, work surface temperature increases of speed further as cutting and tend gradually stable. (3) is in high speed milling, if maintain every tine feed changeless, be in obtain extremely tall data while purify is led, can restrain workpiece temperature rise effectively, this thin to difficult treatment material wall treatment is very favorable. (4) can compare accurate ground to detect like appearance with infra-red heat the dynamic change rule of field of temperature of area of the cutting in high speed mill, better land solved the crucial difficult problem that dynamic cutting temperature detects in process of high speed cutting. CNC Milling