Heat in metal cutting and cutting temperature brief introduction

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Heat in metal cutting and cutting temperature are the phenomenon of another important physics of the generation in cutting process. The work that does when cutting, but the heat of the quantity such as translate into. Result cut heat to be in except a few dissipation all round medium China and foreign countries, the others all passes into cutting tool, in cutting bits and work, make their temperature elevatory, cause workpiece to be out of shape, quicken cutting tool to wear away. Accordingly, research heat in metal cutting and cutting temperature have important economic sense. One, be transformed by cutting result and arise and conducting heat in metal cutting of heat in metal cutting come. Following plan institute are shown, include among them: The hot QP that cuts area work of deformation to form, cut bits and before the hot Qrf that knife face friction work forms, already machined the surface and hind the F of hot Q α that knife face friction work forms, accordingly, 3 calorific area are shared when cutting, cut an area namely, cut bits and before knife surface contact area, hind knife face and already machined the surface to contact an area, be like graphic representation, 3 calorific areas are out of shape with 3 the area is opposite should. So, the origin of heat in metal cutting cuts bits namely before work of deformation is mixed, hind the friction work of knife face. Produce Q of total heat in metal cutting, pass into Qc of the Qch that cut bits, cutting tool, workpiece respectively Qw and all round medium Qr. The formation of heat in metal cutting and conduct a relation to be: The heat in metal cutting when cutting plasticity metal basically is chafed by face of the knife before cutting an area to be out of shape heat is mixed heat is formed; When cutting brittleness metal criterion hind the proportion that heat of knife face attrition holds is more. 2, the computation of cutting temperature and the germ that although heat in metal cutting is cutting temperature rises,measure, but what affect cutting process directly is cutting temperature however, cutting temperature points to the average temperature θ of cutting area commonly. The work of deformation that Nextpage produces through cutting area, friction work and heat are conducted, can push lukewarm area of cipher out cutting to be worth approximately. Cutting temperature is caused by the quantity of heat that total meritorious service uses up to form when cutting. The hot Q of the generation inside unit time is equal to the cutting power Pm that use up, namely the measurement technique of cutting temperature is very much, see figure below. ① is natural thermocouple way is natural thermocouple law basically is to be used at determining the average temperature of cutting area. Legal person of ② artificial thermocouple is versed in thermocouple law is to be used at measuring cutting tool, cut the temperature that the feature assigns on bits and workpiece, use it to be able to get the seat of temperature distributinging field and highest temperature. 3, the main factor basis that affects cutting temperature is analysed theoretically and much experimentation considers to know, cutting temperature basically suffers material of parameter of geometry of cutting dosage, cutting tool, workpiece, cutting tool to wear away the influence with cutting fluid, try to analyse to these a few main factors below. Analyse the each element effect to cutting temperature, basically should be opposite from these elements the quantity of heat of the generation inside unit time and the caloric influence proceed with that come out. If the quantity of heat of generation is more than the quantity of heat that come out, criterion these elements will make cutting temperature heighten; Certain factor makes the quantity of heat that come out increases, criterion these elements will make cutting thermal drop small. Nextpage1.

The influence cutting dosage of cutting dosage is the main factor that affects cutting temperature. Be opposite through measuring lukewarm experiment to be able to find out cutting dosage the influence rule of cutting temperature. Use on lathe normally measure lukewarm device to beg a cutting dosage to concern to the influence of cutting temperature, can arrange following and general formula: Cutting rate is the oldest to cutting temperature influence, follow cutting rate rise, cutting temperature rises quickly. Feed affects take second place to cutting temperature, and when bearing the demanding change that measure Ap, medicinal powder the quantity of heat of hot area and generation also makes corresponding change, reason Ap is very small to the influence of cutting temperature. 2.

The affects O of γ of the horn before cutting temperature θ is followed accretion of parameter of cutting tool geometry and reduce. Because,this is before when horn increases, unit cutting force drops, the cause of reductive of heat in metal cutting that makes arise. But before horn is more than 18 ° ~ after 20 ° , reduce to the influence of cutting temperature, this is make radiator accumulates reduced cause because of wedge horn decrescent. (see a picture 2.

28) when R of Κ of Nextpage tool cutting edge angle is reduced, make cutting width HD increases, cutting ply HD is reduced, accordingly, cutting is out of shape and attrition increases, cutting temperature is elevatory. But after cutting width HD increases, medicinal powder hot condition improvement. Because come loose,heat has main effect, reason decreases as Kr of tool cutting edge angle, cutting temperature drops. Graph 2.

29 be opposite for Kr of tool cutting edge angle the influence curve of cutting temperature. γ of negative B pouring arris 1 be in (0, the change inside 2)f limits, re of radius of circular arc of point of a knife is in 0, 1.

Change inside 5mm limits, basically do not affect cutting temperature. Because lose the accretion of arris width and radius of circular arc of point of a knife, can make plasticity is out of shape the plasticity of the area is out of shape increase, but on the other hand this both can make of cutting tool medicinal powder hot condition is improved somewhat, the quantity of heat that come out also increases somewhat, both tend evenly, affect to cutting temperature so very small. 3.

The affects workpiece data intensity of workpiece material (include hardness) be opposite with coefficient of thermal conductivity the influence of cutting temperature is very big. Know by theoretical analysis, unit cutting force is the main factor that affects cutting temperature, and the intensity of workpiece material (include hardness) decided unit cutting force directly, so workpiece data strength (include hardness) when increasing, the grow in quantity of heat in metal cutting of generation, cutting temperature is elevatory. The coefficient of thermal conductivity of workpiece material affects heat in metal cutting directly derive. 4.

Influence of cutting tool tatty is in hind of knife face wear away after the value reachs fair numerical value, increase to the influence of cutting temperature; Cutting speed heals tall, the influence heals remarkable. The strength of alloy steel is great, coefficient of thermal conductivity is small, so the cutting tool when cutting alloy steel wears away the influence of pair of cutting temperature, compare when cutting carbon steel big. 5.

The to cutting temperature influence of influence cutting fluid of cutting fluid, the heat conduction function with cutting fluid, specific heat, discharge, pouring the temperature of means and itself has very big concern. From the point of heat conduction function, oily kind cutting fluid is inferior to emulsion, emulsion is inferior to fluid of water radical cutting. 4, the cutting temperature influence to workpiece, cutting tool and cutting process cutting temperature is high it is cutting tool tatty main reason, it raises those who restrict productivity; Cutting temperature still can make machine loss of accuracy, make already machined the surface to produce leftover stress and other limitation. (1) the cutting temperature influence to workpiece data strength and cutting force although the temperature when  cutting is very tall, but the influence that cutting temperature reachs intensity to workpiece material hardness not very big; The stress effect that cuts area is not apparent. (2) raise cutting temperature appropriately to the influence of cutting tool material, it is advantageous to raising the tenacity of hard alloy. (3) the influence to work measure precision (4) use speed of cutting of cutting temperature automata or feed (5) use cutting temperature and cutting tool of cutting power control to wear away CNC Milling