The cutting process of dry state hard turning steel part after chilling thermal treatment
Technical field
The present invention is a kind of cutting process, specifically is a kind of cutting process of dry state hard turning steel part after chilling thermal treatment, belongs to the Machining Technology field.
Background technology
Hard attitude turning is meant and utilizes the turning processing of high-performance lathe tool for quenched components consisting (55-65 HRC) that this is fine-processing technique normally.Hard car adopts dry state turning in theory, does not promptly use cooling fluid, has fundamentally removed a big industrial pollution source.Based on this reason, hard turner skill can be counted as a kind of environmental protection processing mode.The main theory foundation of the hard turner skill of dry state is the thermal softening effect; be meant owing to adopt superhard cutter; the hear resistance height of cutter; metal at high temperature produces softening; the shearing resistance of metal material, tensile strength descend; cutter coat can form the thin diaphragm of one deck on rake face, cutting force is reduced, and the surface quality after the part machining improves.And adopt traditional hygrometric state cutting, because the lasting cooling of cooling fluid can't make the metal material of part softening.
The hard turner skill of dry state has the shortcoming that surface roughness is undesirable, the lathe tool life-span is short at present.The present invention effectively solves this two shortcomings by optimizing original technology.
Find Chinese patent ZL03108256.4, patent name: curved surface cutting processing method through literature search to prior art.This patent is a kind of eccentric wear damage of cutter cutter head, curved surface cutting processing method that can prolong the lens life-span of preventing, mention in this patent document: the shape of the cutter head of cutter is made the even shape at band angle, two ends, the cutter head tip line of this cutter is held in parallel with the wiring that leads to as the design curved surface of machined surface, on the surface of blank, carry out turning processing, form 1 wheel belt shape machining face, the state of part superposition forms the 2nd wheel belt shape machining face to stagger also along radial direction cutter.Repeat this processing, make the surface of blank in fact become the polished surface that forms by concentric a plurality of wheel belt shape machining faces along design curve; Whole lens cutter head can be used as cutting zone and irrelevant with the curve form of processing object, the eccentric wear that can prevent cutter head decreases, prolong cutter life, cutter head tip line and the wiring keeping parallelism that leads to curve can be simplified the Position Control of cutter cutter head etc.Carry out preventing in the curved surface cutting working method that the eccentric wear of cutter cutter head from decreasing, can prolong the lens life-span but this patent is meant at use lens cutter head, and be not suitable for common machining, the limitation scope of use is arranged.And this patent do not improve the processing beat, not have to propose the scheme by original blade raising Part Surface Roughness yet.
Summary of the invention
The present invention is directed to the deficiencies in the prior art and defective, a kind of cutting process of dry state hard turning steel part after chilling thermal treatment is provided.Tradition judge to force the standard of tool changing be when Part Surface Roughness constantly overproof, promptly deciding this cutter head scraps, and the present invention continues to keep processing when overproof when Part Surface Roughness is continuous, the processing parts number that prolongs the pressure tool changing is to cross " puppet is scrapped " zone, make lathe tool can continue to use, thereby prolong the life-span of forcing actual cutter head.The present invention has overcome the limitation of prior art, under the processing environment that keeps original hard car lathe tool of use and lathe, has improved Part Surface Roughness, prolongs the number of the processing parts of forcing tool changing at double, significantly improves cutting speed.
The present invention is achieved by the following technical solutions, the present invention uses dried " thermal softening effect " theory of cutting, analyze " puppet is scrapped " phenomenon in its process, broken through the limitation of prior art, by to cutting speed, lathe tool reconditioning parameter, that piece surface is carried out soft coating is coated, and keeps that the methods such as all parameters of road glossing guarantee, improve the Part Surface Roughness of requirement and prolong cutter life behind the part.
Concrete steps of the present invention are as follows:
First: the original Part Surface Roughness (Ra=0.30~0.45 μ m) that requires hard turner skill to reach is in theory required to be reduced to the range of surface roughness (Ra=0.50~0.89 μ m) that the hard Che Suoneng of actual dry state reaches, the hard car of dry state just can have been used smoothly like this, and overproof surface roughness (Ra=0.50~0.89 μ m) is gone to solve by the glossing in road, back.The glossing in road need not be revised any parameter after noting, can reach the requirement of finished surface roughness equally.This is that too high Part Surface Roughness can weaken the effect of polishing on the contrary after the turning because for glossing.
Second: tool setting, the input cutting parameter comprises lathe tool zero point and compensation rate, and machine spindle speed is risen to 300 ~ 700m/min from 90 original ~ 150m/min, but keeps feed rate 0.02mm/r constant.Here the purpose that significantly improves the lathe spindle rotating speed is in order to obtain a higher cutting region temperature (〉=800 ℃), to be favourable to Part Surface Roughness, and can to improve the processing beat.Notice that feed rate (unit is mm/r) is constant, to guarantee machined surface roughness.
The the 3rd: then part is loaded onto the internal expanding vehicle clamper, shut the lathe door.
The 4th: the internal expanding anchor clamps clamp part automatically, and machine tool chief axis begins rotation, drive anchor clamps and clamped part and rotate at a high speed, and the lathe tool feed also begins the turning part conical surface.Feed rate is 0.02mm/r, and monolateral turning amount (cutting depth) is 0.1 ~ 0.2mm, the case hardness 〉=700HV10 of processing parts (60.1HRC).
The 5th: after the cutting of the whole part conical surface finishes, lathe tool cutter relieving, machine tool chief axis stall, the internal expanding vehicle clamper loosens part, the lathe indicator lamp is bright, at this moment opens the lathe door, takes off part, check the surface roughness of part, when Part Surface Roughness Ra 〉=0.8 μ m, continue to keep processing, prolong force tool changing the processing parts number to cross " puppet is scrapped " zone of lathe tool, make lathe tool can continue to use, thereby prolong the life-span of forcing actual cutter head.Part Surface Roughness in the processing of " puppet is scrapped " zone can be guaranteed by road, back glossing fully, and glossing need not be revised any parameter; As the continuous Ra of Part Surface Roughness 〉=0.90 μ m, and when the processing parts number has been greater than or equal to 360, replace lathe tool;
The 6th: the part of the continuous Ra of surface roughness 〉=0.90 μ m that the 5th step is obtained is sent into burnishing machine, and the conical surface of processing parts is polished, and is finished product after the polishing.The technological parameter of polishing is identical with the technological parameter of the part of polishing Ra=0.30~0.45 μ m.
" puppet is scrapped " of lathe tool of the present invention is meant: after lathe tool had cut a collection of part, it was overproof continuous Part Surface Roughness to have occurred, and overproof amount has the trend of rising, and cutter head truly have wearing and tearing, tend to assert that this cutter head scraps.If but continue to use this cutter head, after having cut another batch of part, the good Part Surface Roughness of a new round can appear again, and lathe tool can continue to use, and rate of depreciation is than preceding slow " puppet is scrapped ".
For the hard car of dry state in the defective aspect the Part Surface Roughness, the present invention provides a kind of method, by analyzing " puppet is scrapped " phenomenon in the process, broken through the limitation of prior art, the hard car of dry state is reached require in theory hard car the Part Surface Roughness that can reach, even the Part Surface Roughness that reaches after the polishing requires (can cancel glossing), can will guarantee that cutter life prolongs 1 times than original, can adopt part is carried out alramenting (getting final product about phosphate coating thickness 5 μ m) again.The present invention simultaneously adopts high cutting speed, for hard Vehicle Processing, is that cutting speed raising 5-6 doubly is a very big breakthrough with machine spindle speed.The inventive method has broken through the limitation of dried cutting process for Part Surface Roughness.
Description of drawings
Fig. 1 a is the hard car operation card main technologic parameters before improving, and Fig. 1 b is a conical surface enlarged drawing.Original as seen from the figure theoretic Part Surface Roughness requirement, this requirement is higher.
Fig. 2 a is new cutter head perspective view, and Fig. 2 b is the cutter head perspective view behind 360 parts of cutting.
Fig. 3 a, Fig. 3 b, Fig. 3 c are the illustraton of model that roughness value produces fluctuation.
The specific embodiment
Hard attitude turning object is gearbox model F15 (Sail car) fourth gear driven pulley assembly.Monolateral turning amount (cutting depth) is 0.1mm, the cutting point linear velocity by test be divided into 90,150,300,4 grades of 700m/min, feed rate is that 0.02mm/r is constant, in order to guarantee Part Surface Roughness.Each grade is compact grained 16MnCr5 in conjunction with the ring gear material.Through surperficial cure process, hardness reaches 740-780HV10 (61.8-63.3HRC) in conjunction with the ring gear conical surface, effective carburized (case) depth=0.4-0.8mm, and hardness is 550HV1.(52.4HRC)。Require the case hardness 〉=700HV10 (60.1HRC) behind the hard car, effectively carburized (case) depth 〉=0.3mm.Other cutting parameter is seen Fig. 1 a, Fig. 1 b (the hard car operation card figure before improving)
Cutter adopts agree to receive the hard car lathe tool of DNGA432EMTKB5655 that (KENNA) company produces, and its material is PCBN, and face coat is PVD-TiAlN, anterior angle γ=0 °, r=55 ° of nose angle ε.Cutting lathe is Japanese OKUMA LB250T type speed lathe, and manufacturing procedure is that super finish turning is in conjunction with the ring gear conical surface.Require Ra=0.30~0.45 μ m.
Specific embodiments of the invention below are provided:
Embodiment 1
The projection of new cutter head and old cutter head is amplified, utilize the thermoplasticity flow principles, in conjunction with " puppet is scrapped " phenomenon of the measurement data of Part Surface Roughness being analyzed in its process.
The cutter head projection enlarged drawing of Fig. 2 a, Fig. 2 b, the cutter head right hand edge is a rake face.Fig. 2 a is the projection enlarged drawing of new cutter head.From Fig. 2 b as seen, occur negative rake on the rake face, this is that new blade does not have because in the working angles, part bump cutter head rake face forms.The new original negative chamfered edge of blade cutter head is (because cutting depth is very little, be 0.10mm, this can regard negative rake as) and horizontal angle theta, behind cutting 360 parts, tool wear, negative chamfered edge and horizontal line angle diminish and are θ ', and negative chamfered edge length increases, and the transition arc radius of negative chamfered edge and back knife face also increases.This can explain that the spark of cutting zone constantly strengthens this phenomenon in the process of 360 parts of the 1st part to the of machining.Show also that in this working angles cutting temperature is owing to the expansion of friction zone continues to raise.
Surface roughness value produces the model of fluctuation shown in accompanying drawing 3a, Fig. 3 b, Fig. 3 c.
Do not consider to produce negative rake φ gradually after rake face is impacted, for new cutter head, 1 district, 2 districts and between arc transition (3 district) comparatively favourable (Fig. 3 a) for improving surface roughness; And after having cut some, 1 district (negative chamfered edge) reduces with horizontal sextant angle, and the transition arc in 3 districts is destroyed, forms wedge angle, causes surface roughness decline (Fig. 3 b); Continue cutting, the part to be processed surface is friction 3 district wedge angles constantly, add the high heat that whole friction zone produces and make the whole friction zone generation of knife face plasticity mobile, and wedge angle fades away, and circular arc produces again, the surface roughness that processes can improve again (Fig. 3 c).Afterwards, this circulation begins again to continue, thereby causes surface roughness clocklike to fluctuate.This is the essence of lathe tool " puppet is scrapped ".
Embodiment 2
Original pressure tool changing number (monolateral cutter head) is 200, when being worked into the 200th part, records Ra 〉=0.8 μ m, and cutter head amplify is shown that tool arc is worn, thinks that cutter head scraps fully.
Improving one's methods is that the pressure tool change time is prolonged, and other all machining condition is constant, crosses after " puppet is scrapped " district, and Part Surface Roughness is obviously improved.Cutter head amplify is shown that tool arc forms again, and often to cross the Part Surface Roughness that forms after " puppet is scrapped " district be best.The final tool changing number (monolateral cutter head) of forcing has extended to 320.
Embodiment 3
Cutting speed is brought up to 400m/min by original 90m/min, force tool changing number (monolateral cutter head) to extend to 360.Part Surface Roughness Ra value sees the following form:
15# 0.587 | 30# 0.670 | 45# 0.634 | 60# 0.560 |
75# 0.622 | 90# 0.699 | 105# 0.611 | 120# 0.739 |
135# 0.690 | 150# 0.688 | 165# 0.709 | 180# 0.628 |
195# 0.747 | 210# 0.725 | 225# 0.833 | 240# 0.811 |
255# 0.793 | 270# 0.753 | 285# 0.772 | 300# 0.758 |
315# 0.765 | 330# 0.836 | 345# 0.848 | 360# 0.881 |
Require Ra=0.30~0.45 μ m, the inferior position of the Part Surface Roughness aspect that the effectiveness of the hard car of visible actual dry state should reach with respect to the hard turner skill that requires in theory.If but with these part polishings, we find that all surface roughnesses all reach standard, see the following form:
15# 0.226 | 30# 0.243 | 45# 0.225 | 60# 0.220 |
75# 0.219 | 90# 0.229 | 105# 0.216 | 120# 0.221 |
135# 0.239 | 150# 0.249 | 165# 0.247 | 180# 0.259 |
195# 0.277 | 210# 0.241 | 225# 0.230 | 240# 0.298 |
255# 0.292 | 270# 0.291 | 285# 0.302 | 300# 0.335 |
315# 0.286 | 330# 0.289 | 345# 0.284 | 360# 0.299 |
Require Ra=0.15~0.30 μ m after the polishing, the Part Surface Roughness that records all reaches standard, that is to say, the standard that the Part Surface Roughness value is reduced to the hard car of dry state is fully feasible.
Embodiment 4
Below provide piece surface made phosphatization (getting final product about phosphate coating thickness 5 μ m) and handles after, the Part Surface Roughness that the hard car of dry type is obtained, cutting speed are 400m/min, force tool changing number (monolateral cutter head) to extend to 495.
15# 0.254 | 30# 0.361 | 45# 0.404 | 60# 0.387 |
75# 0.344 | 90# 0.321 | 105# 0.236 | 120# 0.241 |
135# 0.243 | 150# 0.412 | 165# 0.309 | 180# 0.429 |
195# 0.345 | 210# 0.321 | 225# 0.281 | 240# 0.282 |
255# 0.256 | 270# 0.233 | 285# 0.196 | 300# 0.213 |
315# 0.226 | 330# 0.246 | 375# 0.242 | 390# 0.244 |
405# 0.273 | 420# 0.372 | 435# 0.490 | 450# 0.511 |
480# 0.618 | 495# 0.534 | | |
420 parts that can see before all reach in theory Part Surface Roughness and the interstage 210#-405# that the hard turner skill that requires should reach, and just in best sharpening angle excursion, the hard car of dry state has reached polished surface roughness scope.
Embodiment 5
In fact cutting speed can be risen to 700m/min, yes in the scope that lathe allows.During for hard car alramenting parts processed, cutting speed his-and-hers watches The surface roughness affected sees the following form:
Cutting speed V/mmin
-1 | 90 | 150 | 300 | 700 |
Average Ra value/μ m | 0.198 | 0.218 | 0.208 | 0.207 |
This is that the thermal softening effect is not remarkable because cutting output is very little.If what adopt is speed lathe, in the lathe setting range, cutting speed can be risen to 700m/min fully.And, prove that the size and the excursion of the main cutting force of dry state and the hard car of hygrometric state do not have significant difference in the very little hard car process of cutting output by to the main cutting force measurement in the turning process.