Of metallic cut be out of shape discuss
- source:YESCOM CNC Machining
02 - 0.
2mm, so slide surface of commonly used AB expresses the first be out of shape area, AB face also is called cut an area. Nextpage cuts the included angle φ between face AB and cutting speed Vc to call cut corner. The included angle ω between active force Fr and cutting speed Vc calls action part. The first be out of shape the area forms those who cut bits to be out of shape namely area, its are out of shape the characteristic is cut generation cuts slippage to be out of shape. 2) the 2nd be out of shape area (with before the layer cutting bits of knife surface contact arises be out of shape area) inside metallic extruding grinds be out of shape through the first be out of shape after the area, eduction of formation direction of extent of the knife before cutting bits to want an edge, still must overcome the attrition power that the knife before cutting tool faces the extruding that cut bits and produces. generation right now extruding attrition is out of shape. Should point out, the first be out of shape area and the 2nd be out of shape the area is mutual correlation. Before when the attrition muscularity on knife face, the eduction that cut bits is not suitable, extruding is out of shape aggravate, as a result the first be out of shape of the area cut slippage to be out of shape increase. 3) the 3rd be out of shape area (point of close cutting blade already machined what arise inside the surface to be out of shape area) metallic extruding grinds be out of shape the extruding of face of the knife after already machining the surface to be mixed partly by cutting blade blunt circle chafes, cause fiber is changed and machine sclerosis. 2, the magnanimity method of cutting deformation is opposite slippage 1, ε of opposite slippage of opposite slippage ε is to use measurement the 1st be out of shape degree of area slippage metabolic. As above graph, the distance when setting edge of line of the AB in cut to cut face slippage to A"B" is △ Y, in fact △ Y is very small, reason can think slippage is to be in cut aspirant travel, its slippage measures the S that it is △ . ε of opposite slippage expresses to be: 2, a parameter that is out of shape coefficient ∧ H is out of shape coefficient ∧ H is the bulk of change of over all dimension that expresses to cut bits. Following plan institute are shown, after the course that cut bits cuts face of the wind shear form, knife before getting again to chafe, compare with cut, its length shortens, ply increases, this kind of over all dimension that cut bits changes be out of shape the phenomenon calls the systole that cuts bits. Be out of shape coefficient ∧ H shows the rate of the systole that cut bits, namely Nextpage from go up the graph is knowable, cut the influence that horny φ changes to contract to cutting bits, φ increases cut face AB to decrease short, hch of the ply that cut bits is reduced, decrescent of reason ∧ H. The concern between them is as follows: From above two formula are knowable, cut corner φ and before horny γ 0 it is influence cutting metabolic two main factors. If increase before horny γ 0 and cut horny φ , make opposite slippage ε , be out of shape coefficient ∧ H is reduced, criterion cutting is out of shape reduce. Attention: Because cutting process is a very complex physics process, cutting is out of shape besides generation slippage is out of shape outside, still have the effect such as extruding, attrition, and ε value is main from cut wind shear form to consider; And ∧ H basically reduces respect analysis from plasticity. So, ε and ∧ H can express cutting deformation approximately only. 3, cutting horn to cut horny φ surely really is influence cutting metabolic a main factor. If can calculate the cost that cuts horny φ , be out of shape to understanding and control cutting have important sense. For this, a lot of scholars had a large number of research, recommended a certain number of computation pattern that cut horny φ . Among them, will decide the computational pattern that cuts horny φ is by least energy principle: Press the theory of the greatest shearing stress, beg piece cut type of horny φ computation to be: From above formula can see: φ and γ 0, β is concerned. γ of the horn before increasing 0, reduce β of angle of friction, make cut horny φ to increase, cutting is out of shape reduce, this one pattern already was used generally in manufacturing practice. From above formula also can see: The 2nd attrition that is out of shape the area arises is right the 1st influence rule that is out of shape the area cuts wind shear contrast. 4, the formation of the tumour that accumulate bits reachs his to be in to the influence of cutting process cutting rate is not high and can form the condition that cuts bits continuously to fall, when processing general steel makings or other plasticity data, often place of advanced knife face is adhesion a section plane shows three cornuted nugget sometimes. The metal on advanced knife face calls this cold welding the tumour that accumulate bits (or knife tumour) . Its hardness is very tall, be workpiece material normally 2, 3 times, when be in stabler condition, can replace edge to undertake cutting. 1, how is the tumour that accumulate bits formed? 1) the attrition that surface contact of the knife before cutting bits to be opposite is in, face of the knife before making is very clean. 2) reach constant temperature when both interface at the same time pressure taller when, can produce felt phenomenon, namely general so called " cold welding " . Cut bits from the ground floor that is stuck in knife face genteel over- , form " inside attrition " . 3) if temperature and pressure are proper, the metal above ground floor because inside chafe and be out of shape, also can produce treatment sclerosis, and ground floor be been in by block sluggish, stick into an organic whole. 4) such felt layers are brought up stage by stage, till the temperature till the place and pressure can't cause conglutinate. The Nextpage2, condition that forms the tumour that accumulate bits: Main decision at cutting temperature. In addition, the element such as the pressure between interface, crude rate, bonding strength is concerned with the condition that forms the tumour that accumulate bits. 1) say commonly, the treatment sclerosis tendency of plasticity material heals strong, more easy generation accumulates bits tumour; 2) temperature and pressure are too low, won't produce the tumor that accumulate bits; Conversely, temperature is too high, generation changes intention infirmly, also won't produce the tumor that accumulate bits. 3) when feed keeps certain, height of the tumour that accumulate bits and cutting speed have affinity. 3, the influence of the tumour that accumulate bits to cutting process 1) actual before the horn before what horn increased it to increase cutting tool is actual, can make cutting force is reduced, have positive effect to cutting process. The tumour that accumulate bits heals tall, actual before horn heals big. 2) the floor that makes machine exterior surface roughness to increase the tumour that accumulate bits is relatively a few stabler, its coping is very flabby calm, easy burst, one part is added at cutting bits repeatedly bottom and eduction, one part remain is being machined apparently, the tumour that accumulate bits is bulgy edge part makes machine the surface to be cut very coarsely, because this is when finish machining,must try avoid or reduce the tumor that accumulate bits. 3) accumulate bits tumour conglutinate to the influence of cutting tool life on advanced knife face, when relative stability, replaceable edge cutting, have reduce cutting tool to wear away, the function that improves life. But when hard alloy cutting tool is being used below the situation that does not stabilize quite in the tumour that accumulate bits, the burst of the tumour that accumulate bits makes grain of hard alloy cutting tool flakes likely, make wear away instead aggravate. 4, the main method that prevents the tumour that accumulate bits 1) lower cutting rate, make temperature inferior, felt phenomenon happens not easily; 2) use high speed cutting, make cutting temperature prep above accumulates the corresponding temperature that bits tumour disappears; 3) the cutting fluid with use lubricant property good, reduce attrition; 4) the horn before increasing cutting tool, cut in order to reduce bits and before knife surface contact the pressure of the area; 5) raise workpiece material hardness appropriately, reduce treatment sclerosis liability. Nextpage5, cutting is out of shape metabolic rule from opposite slippage ε , be out of shape coefficient ∧ H is calculated in type knowable, cut corner φ and before horny γ 0 it is influence cutting metabolic two main factors. If increase before horny γ 0 and cut horny φ , make opposite slippage ε , be out of shape coefficient ∧ H is reduced, criterion cutting is out of shape reduce. 1, before horn: γ of the horn before increasing 0, make cut horny φ to increase, be out of shape coefficient ∧ H is reduced, accordingly, cutting is out of shape reduce. Manufacturing practice makes clear: Use big before cutting of horny cutting tool, edge it is sharp, easy to cut a metal, cut bits and before length of knife surface contact reduces short, resistance drifting bits small, accordingly, cutting is out of shape save labour of small, cutting. 2, cutting speed: Cutting speed Vc is to pass the tumour that accumulate bits to make cut horn to φ is changed and pass cutting to temperature makes μ of coefficient of friction changes and affect cutting metabolic. Cutting speed Vc is right be out of shape the influence of coefficient: 3, feed: Feed F increases, h of metabolize coefficient ∧ is reduced. Feed F affects the pattern to cutting metabolic: 4, workpiece material: Workpiece material hardness, intensity rises, cutting is out of shape decrease. CNC Milling CNC Machining