Contain the hot model research that integrates area structure
- source:SHNMIN CNC Machining
The Established Thermal Model Are Approved By A Practical Test.
It Shows That There Is A Good Calculating Accuracy For A Thermal Model In Consideration With The Influence Of Contact Thermal Resistance On Interface Structure.
Key Words: Interface, contact Thermal Resistance, thermal Model1 is introductive a machinery always is assembled by a lot of component and become, accordingly, put inevitably in the combinative position with various moves. Deliver in machinery when thermal current when, want to shed classics component itself not only, and should shed classics union position, in passing into the another component that is linked together to it through tying place. Because link the existence of the face, make of thermal current deliver produced change, compare to the obstruction photograph of thermal current with material itself interior, union faces thermal current to still have a kind of greater resistance. The obstruction action that this kind of union faces heat to deliver is osculatory thermal resistance with respect to what say. The thermal resistance character that combines an aspect is conducted to machine tool caloric, segregation and from this and formation temperature field and heat are out of shape having quite big effect. Those who combine pressure, medium is structural noumenon material and condition of combinative scale face, different, consociate face conducts heat coefficient has severalfold even the difference of ten times, from this and difference of brought temperature field, hot metabolic is cannot of oversight  . But because research is inadequate, still do not have the statistical result of this respect. The market is at present genteel all sorts of CAE software of travel, although the function is very complete, calculated capacity is very strong, but still cannot solve combinative scale problem. It is to lack character of all sorts of general combinative scale base data; 2 it is the applied skill that lacks these data and software interface. So, these software still cannot be used forecast mechanical and overall character. Reach its to be in what the applied technology in building a model has development to discuss to integrating character of surface contact thermal resistance only, ability is opposite in implementation of blueprint design phase mechanical and overall heat is forecasted characteristicly, discover weak point, put forward in time to revise a proposal, the actor that reachs a variety of plan is chosen. The research result that butt joint of 2 contacts thermal resistance hits thermal resistance 40 time evening, through 50 old research, already obtained a lot of positive result, be in especially nuclear reactor, heat engine and hot equipment, plane, space flight implement wait for a respect to get applied. Because machining center reachs automation direction development to efficient, high spirit, the application in contacting thermal resistance character to be designed in the machine tool so puts forward clearly also. Form of conjugate of scale of commonly used to the machine tool union had the writer relatively systematic thermal resistance experiments  , the result makes clear: Below the case with medium of scale of quality, union is machined particular in surface of conjugate material, contact, the osculatory thermal resistance of unit area can express to be unit area the function of pressure, namely of of of of of of of of of of of of of Rc=a+b/Pn (1) the Rc in type -- unit area contacts thermal resistance, m2.
℃ / Pn of of W -- contact apparently unit area pressure, a of of MPa , B -- wait for calm coefficient, wait for concerned graph with quality of treatment of conjugate material, surface, medium the 1 partial test result that is osculatory thermal resistance. Graph the partial test result of 1 contact thermal resistance 3 fictitious dilate are unit to be in overall the effect that thermal resistance of combinative surface contact reflects to be conducted to heat in hot model, differentiate the unit near combinative scale especially special unit -- fictitious dilate is unit, its special place is not on its dimension, go up in its unit characteristic parameter however. Say for fictitious unit, because unit of scale of this kind of union is dummy,be, their material physics character, conduct heat characteristic, unit attrib border condition all place of actual component part is not had, the thermal resistance that combines an aspect to reflect however is characteristic and ad hoc a kind of unit; Say for outspread unit, because combine this kind unit characteristic to expand go in the unit with adjacent of combinative scale posture,be, is the one fraction that contacts area not merely. In building a model actually, differentiating unitly is the dimension of actual structure takes according to decide, the dimension that joins fictitious and outspread unit namely but go ahead of the rest is affirmatory, again the size according to thermal resistance of combinative surface contact, roll out this kind of unit equivalent thermal conductance. In order to reflect the effect of thermal resistance of combinative surface contact. Set component part the thermal conductance of 1 is λ 1 [W/(m.
℃ ) ] , the thermal conductance of 2 is component part λ 2 [W/(m.
℃ ) ] , fictitious and outspread unit is in component part 1 in along union the dimension of face normal direction is δ 1(m) , in component part 2 in it is δ along the size that combines face normal direction 2 (M) , issue type to hold water apparently. (2) J of the λ in type -- the equivalent thermal conductance with fictitious unit dilate, w/(m.
℃ ) Rc of -- thermal resistance of combinative surface contact, m2.
℃ / W the physical parameter E to the other in fictitious and outspread unit, μ , C (the line bilges coefficient) decide really, basically consider from hot metabolic angle. The size that because combine the surface,goes up in direction of combinative scale normal is very small, so negligible the heat that this one part produces because of temperature rise is out of shape. Accordingly, fictitious and outspread unit is in combinative scale component part 1 medium part, still take component part the E1 of 1, μ 1 with C1, and in component part 2 medium parts, take component part the E2 of 2, μ 2 with C2. The bed of horizontal general be open to traffic with one model is 4 application example exemple, to its box of main shaft, main shaft and lathe bed system undertook the model is calculated building, undertook comparative with actual measurement value, its pursue it is thus clear that as a result 2 with subordinate list. Can see from this, the hot model that considers to combine surface contact thermal resistance to affect has better computational precision. Graph the horizontal of positional subordinate list that part of bed of be open to traffic of 2 horizontal general measures lukewarm place is common of result of lathe temperature field nod a test to be worth quite (K) computation is worth (K) the influence that the influence oversight that considers to combine an aspect combines an aspect 1315.
Character of thermal resistance of surface contact of union of 3915 conclusion research reachs his to be in overall the applied technology in hot model, mechanical and overall hot character can be forecasted accurately in blueprint design phase. Conduce to discover a problem as early as possible, improve design quality. CNC Milling CNC Machining