CN103627880B - Modulus is in the mid-frequency induction hardening technique of the heavily loaded tooth bar of 50mm≤m≤150mm - Google Patents
Modulus is in the mid-frequency induction hardening technique of the heavily loaded tooth bar of 50mm≤m≤150mm Download PDFInfo
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Abstract
The present invention relates to the thermal treatment of super-modulus tooth bar, especially a kind of modulus is in the mid-frequency induction hardening technique of the heavily loaded tooth bar of 50mm≤m≤150mm, inductor block is the suitable profiling inductor block of the teeth groove section form of shape and tooth bar, comprises the steps: A, is placed on by tooth bar on mid-frequency induction hardening lathe; B, by inductor block, the flank of tooth of tooth bar teeth groove and tooth root to be heated simultaneously; C, air-cooled, rate of cooling is greater than critical cooling rate, and air-cooled rear tooth bar heating zone surface temperature is positioned at martensite range; After D, thermograde within the scope of the depth of hardening zone on top layer, tooth bar heating zone are stable, implement liquid cooling, complete structural transformation, the rate of cooling of liquid cooling is greater than critical cooling rate.This technique can ensure that tooth bar obtains higher hardness and comparatively deep-hardening layer, effectively improves the stressed condition at tooth root place simultaneously, avoids tooth root to ftracture and delayed fracture, is applicable to the quenching of super-modulus tooth bar, especially foundry goods super-modulus tooth bar.
Description
Technical field
The present invention relates to the thermal treatment of super-modulus tooth bar, and especially a kind of modulus is in the mid-frequency induction hardening technique of the heavily loaded tooth bar of 50mm≤m≤150mm.
Background technology
Gear, rack mechanism are important drive disk assemblies, also be conventional long distance type of drive, compared with other mechanical transmission forms such as band, chain, friction, hydraulic pressure, screw mandrel, there is transmission accuracy and efficiency is high, stable drive, supporting capacity are strong, power range is large, good reliability, can the advantage such as low, the long service life of indefinite length docking continuity, compact construction, cost, be widely used in industries such as machinery, aviation, instrument, become the drive disk assembly that all kinds of machinery is indispensable, occupy an important position in modern mechanical manufacturing industry.Wherein, tooth bar is as important basi components, and its quality, performance, life-span directly have influence on the technico-economical comparison of complete machine.
Along with the extensive application of all kinds of big machinery lift technique, the demand of tooth bar is increased day by day.The production of current tooth bar, just towards large modulus, the development of exceeding length both direction, especially modulus is at the super-modulus heavy-duty gear rack mechanism of 50mm≤m≤150mm, be usually used in that some are large-scale, the jacking system of large equipment, as the self-elevating ocean platform jacking system of offshore oil exploitation, the lifting drive of rack-and-pinion climbing type vertical ship lift ship lift chamber.
The manufacture of super-modulus gear and rack belongs to limit processing, with high content of technology, especially the quenching technology of super-modulus tooth bar especially whole system manufacture in bottleneck problem.For large modulus heavy duty tooth bar, for ensureing its strong wear resistance, the hardness that usual requirement is higher, require darker hardened layer, if hardened layer is more shallow, then tooth bar is when working load is heavier simultaneously, because zone of transition has larger quenching to remain tensile stress, this stress is superimposed with the contact stress in work, zone of transition can be made to produce fatigue cracking and expand to the flank of tooth, very easily cause hardened layer easily to peel off from zone of transition; Secondly, for strengthening the bending strength of tooth, require that quench-hardened case is along the flank of tooth, tooth root continuous distribution, if quench-hardened case ends at tooth root, then during rack work, because tooth root place is transition zone tissue, its quenching residual stress is tensile stress, this stress is superimposed with the tensile stress that formed in work, very easily makes tooth root crack.For certain 3000 tonnes of ship-lifter tooth bar, due to its shape, structure, foundry goods can only be adopted; Meanwhile, require that tooth bar is wear-resisting, high-strength, high tenacity, depth of hardening zone requires to reach >=5mm, surface hardness requirement >=HV520, and needs the controlling distortion when quenching.
But current, the thermal treatment process of conventional super-modulus tooth bar, mainly contains two kinds: one, be mainly applicable to the situation of effects on surface hardness without special high request, overall Tempering and Quenching, and modifier treatment is finished heat treatment; Two, be mainly applicable to the situation of depth of hardening zone without special high request, adopt forging, after conditioning heat treatment, carry out hard surfacing or carburizing and quenching process, depth of hardening zone is generally only about 3 ~ 4mm.Therefore, existing normative heat treatment technique all can not meet the requirement to large modulus heavy duty tooth bar performance.
In order to solve the problem, Shanghai Heavy Machines Plant Co., Ltd has carried out correlative study, and in " intermetallic composite coating (hot-work) " of the 13rd phase in 2011, delivered the paper being entitled as " large-scale tooth bar mid-frequency induction hardening test and mass analysis ".Wen Zhong, tooth bar is foundry goods, adopts G42CrMo4 steel alloy to make; Its thermal treatment process comprises: A, modulation treatment, and modulation quenching adopts immersion oil cooling; B, employing monodentate carry out hard surfacing along flank profil continuous quenching method to the flank of tooth of tooth bar and tooth root simultaneously, and the type of cooling is that water-jet sprays, and heat-eliminating medium is aqueous solutions of polymers; C, low-temperaturetempering.According to the detection in literary composition, its tooth face hardness is about 600HV, effective depth of hardening is about 7mm, and tooth root hardness is about 540HV, effective depth of hardening is about 5mm.
But applicant finds, quenching technology in above-mentioned paper, although large modulus heavy duty tooth bar can be met to the requirement along the flank of tooth, tooth root continuous distribution of hardness, depth of hardening zone and quench-hardened case, but it adopts the Cooling Mode of spraying cooling fluid, the potential unfavorable unrelieved stress in tooth bar tooth root place cannot be eliminated and product is used to the disadvantageous effect produced, easy generation quenching crack and distortion, even if product does not find cracking, in use also very easily affect complete machine and use due to delayed cracking.Therefore, anxious new technique to be developed is to meet the requirement to large modulus heavy duty tooth bar performance.
Summary of the invention
Technical problem to be solved by this invention is to provide the mid-frequency induction hardening technique of a kind of modulus at the heavily loaded tooth bar of 50mm≤m≤150mm, this technique can ensure that tooth bar obtains higher hardness and comparatively deep-hardening layer, and effectively improve the stressed condition at tooth root place, the hardening break avoiding tooth root place unrelieved stress to cause and delayed fracture.
The technical solution adopted for the present invention to solve the technical problems is:
Modulus in the mid-frequency induction hardening technique of the heavily loaded tooth bar of 50mm≤m≤150mm, adopt the inductor block of mid-frequency induction hardening lathe to be the suitable profiling inductor block of the teeth groove section form of shape and tooth bar, comprise the steps:
A, tooth bar is placed on mid-frequency induction hardening lathe;
B, heated the flank of tooth of tooth bar teeth groove and tooth root by inductor block, tooth bar heating zone, after completing heating, all reaches quenching temperature within the scope of the depth of hardening zone on top layer, tooth bar heating zone simultaneously;
C, tooth bar is completed heating heating zone implement air-cooled, air-cooled rate of cooling is greater than critical cooling rate, and air-cooled rear tooth bar heating zone surface temperature is between martensite start temperature and martensite finish transition temperature;
D, tooth bar complete air-cooled after, and through conduction of heat, after the thermograde within the scope of the depth of hardening zone on top layer, tooth bar heating zone is stable, implement liquid cooling to heating zone, complete structural transformation, the rate of cooling of liquid cooling is greater than critical cooling rate.
Further, in described step B, adopt continuous induction heating, inductor block is along the continuous induction heating of facewidth direction exercise.
Further, in described step B, adopt the continuous induction heating of monodentate, only the wall scroll teeth groove of tooth bar is heated at every turn, the heating that B completes whole tooth bar is respectively repeated steps to each teeth groove of tooth bar.
Further, described mid-frequency induction hardening lathe is provided with the spray cooling device adjacent and servo-actuated with inductor block; In described step C, to spray cooling device ventilation, implement continuously air-cooled along moving of facewidth direction to tooth bar heating zone with inductor block; In described step D, pass into cooling fluid to spray cooling device, along moving of facewidth direction continuous liquid cooling is implemented to tooth bar heating zone with inductor block; The hard surfacing that B, step C and step D complete whole tooth bar is respectively repeated steps to each teeth groove of tooth bar.
Preferred as one, described spray cooling device is positioned at the below of inductor block, and in described steps A, when placing tooth bar, the facewidth direction of tooth bar is perpendicular to horizontal direction, and in step B, step C and step D, inductor block all moves from the bottom to top along facewidth direction.
Preferred as one, ventilate to spray cooling device while implementing heating through inductor block, with the motion of inductor block, synchronous completing steps B and step C; Complete heating and air-cooled after, close inductor block and stop to spray cooling device ventilate, then pass into cooling fluid to spray cooling device, with the motion completing steps D of inductor block.
Further, link together back-to-back for two pieces tooth bar, make two pieces tooth bar form an entirety, and the tooth of two pieces tooth bar is symmetrically distributed in both sides; In step the two pieces tooth bar linked together is placed on mid-frequency induction hardening lathe, in the subsequent step of steps A, synchronous processing is carried out to the corresponding teeth groove of the two pieces tooth bar linked together.
Preferred as one, described tooth bar adopts CrNiMo cast steel material to make.Optimum, described tooth bar adopts G35CrNiMo6-6 material to make; In step B, after requiring heating, it is 750 ~ 950 DEG C in the temperature at depth of hardening zone place, tooth bar heating zone; In step C, the temperature of air-cooled rear rack surface is 200 ~ 400 DEG C.Preferred as one, in described step C, pass into pressurized air to spray cooling device; In described step D, pass into water-based quenching medium to spray cooling device.
The invention has the beneficial effects as follows: quenching technology of the present invention, the step cooling mode of liquid cooling is added by air cooling, after making final quenching, in quenched zone, the comprehensive action effect of thermal stresses and structural stress shows as stress, thus can ensure that tooth bar obtains higher hardness and comparatively deep-hardening layer, effectively improve the stressed condition at tooth root place simultaneously, the hardening break avoiding tooth root place unrelieved stress to cause and delayed fracture, meet the use properties of tooth bar.
Embodiment
Below in conjunction with embodiment, the present invention is further described.
Modulus of the present invention in the mid-frequency induction hardening technique of the heavily loaded tooth bar of 50mm≤m≤150mm, adopt the inductor block of mid-frequency induction hardening lathe to be the suitable profiling inductor block of the teeth groove section form of shape and tooth bar, comprise the steps:
A, tooth bar is placed on mid-frequency induction hardening lathe;
B, heated the flank of tooth of tooth bar teeth groove and tooth root by inductor block, tooth bar heating zone, after completing heating, all reaches quenching temperature within the scope of the depth of hardening zone on top layer, tooth bar heating zone simultaneously;
C, tooth bar is completed heating heating zone implement air-cooled, air-cooled rate of cooling is greater than critical cooling rate, and air-cooled rear tooth bar heating zone surface temperature is between martensite start temperature and martensite finish transition temperature;
D, tooth bar complete air-cooled after, and through conduction of heat, after the thermograde within the scope of the depth of hardening zone on top layer, tooth bar heating zone is stable, implement liquid cooling to heating zone, complete structural transformation, the rate of cooling of liquid cooling is greater than critical cooling rate.
For ensureing the depth of hardening zone of super-modulus heavy duty tooth bar, technique of the present invention adopts Medium frequency induction hard surfacing equally, and the modulation treatment before quenching and the low-temperaturetempering after quenching adopt existing technique to carry out.But distinguish with existing Medium frequency induction hard surfacing, Medium frequency induction hard surfacing of the present invention adopts the step cooling mode of first air-cooled liquid cooling again.Above-mentioned critical cooling rate, quenching temperature and austenitic transformation critical temperature, martensitic transformation to start with final temperature etc. by steel grade according to reference books, as " thermal treatment handbook ", relevant criterion etc. carry out inquiring about and setting; According to quenching temperature, depth of hardening zone, the electrical parameter of mid-frequency induction hardening requires that bonding apparatus related data sets.
The step cooling mode of quenching technology of the present invention, first by air-cooled, tooth bar heating zone is cooled, by air-cooled quick reduction tooth bar heating zone surface temperature, air-cooled rear tooth bar heating zone surface temperature is between martensite start temperature and martensite finish transition temperature, hardened area temperature can reduce by surface air-cooled and air-cooled period and matrix thermal conduction afterwards, after thermograde within the scope of the depth of hardening zone on top layer, tooth bar heating zone is stable, within the scope of the depth of hardening zone making top layer, air-cooled rear tooth bar heating zone, temperature is all near martensite start temperature, by relaxing process of cooling, the effect of effective minimizing thermal stresses, then, cooled fast by liquid cooling, quickly through metastable austenite district, complete martensitic transformation.The step cooling mode of liquid cooling is added by air cooling, after making final quenching, in quenched zone, the comprehensive action effect of thermal stresses and structural stress shows as stress, thus can ensure that tooth bar obtains higher hardness and comparatively deep-hardening layer, effectively improve the stressed condition at tooth root place simultaneously, the hardening break avoiding tooth root place unrelieved stress to cause and delayed fracture, meet the use properties of tooth bar.Above-mentioned heating zone, the region that namely tooth bar is relative with inductor block; Thermograde within the scope of the depth of hardening zone on top layer, described tooth bar heating zone is stablized, temperature variation by surface, tooth bar heating zone judges, air-cooled rear surface temperature rises under conduction of heat, can judge that thermograde is stablized when ascendant trend stops.
Quenching technology of the present invention, can adopt continuous induction heating, also can adopt induction heating simultaneously.Wherein, induction heating simultaneously, namely workpiece needs the whole sensed device in region hardened to surround, and implements Cooling Quenching after electrified regulation to quenching temperature; Continuous induction heating, i.e. workpiece and inductor block relative movement, make heating continuously carry out.But super-modulus tooth bar, even if sectional making, its scale of construction is also comparatively large, and therefore, best, in described step B, adopt continuous induction heating, inductor block is along the continuous induction heating of facewidth direction exercise.Further, in described step B, adopt the continuous induction heating of monodentate, only the wall scroll teeth groove of tooth bar is heated at every turn, the heating that B completes whole tooth bar is respectively repeated steps to each teeth groove of tooth bar.
Same, the cooling after heating, can adopt the spray cooling device adjacent and servo-actuated with inductor block to implement spraying cooling, workpiece also can be adopted to soak cool in quenching tank.As: when placing tooth bar, the facewidth direction of tooth bar is parallel to horizontal direction, and each teeth groove of inductor block to tooth bar heats from the bottom to top respectively; After often completing the heating of a teeth groove, first carry out air-cooled by air-blast device to this tooth bar, then tooth bar moves down in the heat-eliminating medium of this teeth groove dip quench groove.
But when adopting continuous induction heating, soak the type of cooling into quenching tank, teeth groove final quenching performance everywhere may be caused inconsistent.Therefore, adapt with continuous induction heating, described mid-frequency induction hardening lathe is provided with the spray cooling device adjacent and servo-actuated with inductor block; In described step C, to spray cooling device ventilation, implement continuously air-cooled along moving of facewidth direction to tooth bar heating zone with inductor block; In described step D, pass into cooling fluid to spray cooling device, along moving of facewidth direction continuous liquid cooling is implemented to tooth bar heating zone with inductor block; The hard surfacing that B, step C and step D complete whole tooth bar is respectively repeated steps to each teeth groove of tooth bar.
In order to ensure that teeth groove finally quenches the consistent of performance further everywhere, in step B, step C and step D, inductor block motion is consistent, simultaneously, in order to avoid cooling fluid is on the impact of adjacent sheaves and Adjacent heating zones, ensure quenching performance and processing efficiency, best, described spray cooling device is positioned at the below of inductor block, in described steps A, when placing tooth bar, the facewidth direction of tooth bar is perpendicular to horizontal direction, in step B, step C and step D, inductor block all moves from the bottom to top along facewidth direction.
In order to improve quenching performance further, shortening the timed interval between heating and cooling, and improving processing efficiency, ventilate to spray cooling device while implementing heating through inductor block, with the motion of inductor block, synchronous completing steps B and step C; Complete heating and air-cooled after, close inductor block and stop to spray cooling device ventilate, then pass into cooling fluid to spray cooling device, with the motion completing steps D of inductor block.
Further, link together back-to-back for two pieces tooth bar, make two pieces tooth bar form an entirety, and the tooth of two pieces tooth bar is symmetrically distributed in both sides; In step the two pieces tooth bar linked together is placed on mid-frequency induction hardening lathe, in the subsequent step of steps A, synchronous processing is carried out to the corresponding teeth groove of the two pieces tooth bar linked together.Because the deformation direction of two pieces tooth bar in quenching process is contrary, therefore can counter-force each other, the distortion of tooth bar can be effectively prevent, ensure the form and dimensional precision of tooth bar after quenching.Conveniently connect, preferably adopt connecting tooling to link together back-to-back for two tooth bars, the form of connecting tooling can be arbitrary.
The selection of material prepared by relevant tooth bar, can in the existing various steel grade for the preparation of super-modulus tooth bar, the moulding process requirement of bonding apparatus requirement, blank, the CCT curve of steel grade and air-cooled cooling power are selected, its selection should meet the prerequisite of quenching: Heating temperature, more than austenite stagnation point, obtains austenite; Rate of cooling is greater than critical cooling rate, also namely ensures that it can not meet the nose of its CCT curve in process of cooling, and then obtains martensite or bainite.
Best, described tooth bar adopts CrNiMo cast steel material to make.Wherein, the lattice parameter of Ni is close with γ-iron, can become continuous solid solution, be conducive to the hardenability improving steel, reduce stagnation point and increase austenitic stability, reduce quenching temperature, improve hardening capacity, time same Cr, W or Cr, Mo combine, hardening capacity can increase especially; Cr is medium carbide forming element, in all various carbide, chromium carbide is the most tiny one, it can be evenly distributed in steel volume, make it have high intensity, hardness, yield-point and high wear resistance, Cr can reduce critical cooling velocity when quenching simultaneously, contributes to martensite and is formed and improve martensitic stability, improve hardening capacity, reduce quenching strain; Mo and Cr, Ni combine can improve hardening capacity, crystal grain thinning greatly, improves toughness.Secondly, CrNiMo cast steel erosion resistance, can be adapted to the environment for use of super-modulus heavy duty tooth bar.
Preferred as one, tooth bar adopts G35CrNiMo6-6 material to make.G35CrNiMo6-6 is cast steel material, according to DINEN10293-2005 steel casting material standard, its percentage composition is: C0.32% ~ 0.38%, Si≤0.60%, Mn0.60% ~ 1.00%, P≤0.025%, S≤0.020%, Cr1.40% ~ 1.70%, Mo0.15% ~ 0.35%, Ni1.40% ~ 1.70%.G35CrNiMo6-6 material, because chromium, nickel content significantly increase, the continuous velocity of transformation of metastable austenite slows down, even if adopt slower speed of cooling also can not meet the nose of its CCT curve, also namely under slower speed of cooling, also can be transformed into martensite completely, the air-cooled realization adding liquid cooling step cooling mode can be facilitated.In order to improve hard surfacing hardness further, improve the metallurgical quality of steel, reduce gas content, to reduce nonmetal inclusion, prevent various casting defect on the impact of quenching, preferably control carbon content 0.34 ~ 0.37%, hydrogen richness reaches below 2ppm, oxygen level reaches below 25ppm, nitrogen content reaches below 100ppm.
For the tooth bar that G35CrNiMo6-6 material is made, in step B, after requiring heating, it is 750 ~ 950 DEG C in the temperature at depth of hardening zone place, tooth bar heating zone; In step C, the temperature of air-cooled rear rack surface is 200 ~ 400 DEG C.Induction heating is endogenous pyrogen, and surface temperature fluctuation is large, also cannot to tooth bar internal temperature implementing monitoring, therefore, before enforcement, should bonding apparatus data, be determined by experiment the relation of parameter with depth of hardening zone place, heating zone temperature of the concrete mid-frequency induction hardening lathe adopted.Air-cooled rear rack surface temperature is between 200 ~ 400 DEG C, just in the martensite range of G35CrNiMo6-6 material, also be that temperature is between martensite start temperature and martensite finish transition temperature, after this liquid cooling is adopted again, tooth bar is cooled fast, makes tooth bar complete martensitic transformation.If the temperature of air-cooled rear rack surface is less than 200 DEG C, top layer completes martensitic transformation, the inside latent heat treatment of workpiece, and rack surface temperature is improved, the tissue finally obtained may be non-fully martensitic stucture, thus affects tooth bar depth of hardening zone and performance; After air cooling, the temperature of rack surface is greater than 400 DEG C, and tooth bar internal and external temperature gradient is little, is unfavorable for the improvement of stressed condition.The setting of air cooling parameter, comprehensive rate of cooling requires and inductor block translational speed sets.Because induction heating is endogenous pyrogen heating, and affect by factors such as air cooling airflow fluctuation, internal heat transfer, surface temperature fluctuation strengthens, and therefore, the surface temperature after air cooling only requires to control within the scope of 200 ~ 400 DEG C, does not require to implement accurately to control to it.
Air-cooled gas can adopt nitrogen, rare gas element etc., only need ensure its cooling performance.In order to reduce costs, best, adopt air, also namely in described step C, pass into pressurized air to spray cooling device.Cooling fluid in described step D can adopt any existing liquid quenching medium, but should meet the requirement of quenching cooling rate, avoids the nose encountering CCT curve, ensures the final quenching structure obtained.Wherein best, in described step D, pass into water-based quenching medium to spray cooling device.Water-based quenching medium, the water-soluble solution be made up of a kind of organic polymer and corrosion inhibitor of liquid state, have polyvinyl alcohol water solution and three glass gall solution etc., cooling power is between water and oil.When workpiece is quenched into water-based quenching medium, workpiece surface forms one deck steam film and layer of gel film, and two membranes makes heated parts cool; After entering boiling stage, film breaks, work-piece cools is accelerated, when reaching low temperature, polyvinyl alcohol gel film is formed again again, and work-piece cools speed declines again, so this solution is low in high and low warm area cooling power, high in middle warm area cooling power, effectively can improve residual stress distribution.
Embodiment
In certain factory, engineering test has been carried out in quenching technology design according to the present invention, sample tooth bar is foundry goods, G35CrNiMo6-6 material is adopted to make, tooth bar modulus 66.667mm, tooth depth 141mm, facewidth 810mm, every part tooth bar, containing 24 teeth, require depth of hardening zone >=5mm, surface hardness >=HV520.Before quenching, carry out modified by existing technique according to DINEN10293-2005 steel casting material standard.
Before quenching, two pieces tooth bar is linked together through connecting tooling is back-to-back, two pieces tooth bar is made to form an entirety, and the tooth of two pieces tooth bar is symmetrically distributed in both sides, connecting tooling adopts that the patent No. of the applicant is ZL201120545825.3, denomination of invention for super-modulus tooth bar table quench anti-deformation tool utility model patent described in frock.
Before enforcement, require and equipment data in conjunction with quenching temperature by depth of hardening zone requirement, be determined by experiment the parameter of the concrete mid-frequency induction hardening lathe adopted, test method adopts boring method, carries out temperature detection at the distance flank of tooth and tooth root 5mm place welding heat galvanic couple.During due to induction heating, after temperature exceedes Curie temperature, permeability reduces, and induced current penetration depth, rate of heating change thereupon, and therefore in the heat-processed of whole tooth bar, parameter is dynamic, but not definite value.Parameter setting, shown in table 1 specific as follows, the temperature of each embodiment is regulated in proportion by movement velocity.
The parameter of table 1, mid-frequency induction hardening lathe
| Gap | Movement velocity | Frequency | Voltage | Electric current | Apart from surperficial 5mm place |
| mm | mm/min | KHz | V | A | ℃ |
| 6±1 | 150～400 | 3.1～3.9 | 450～550 | 320～400 | 750～950 |
The mid-frequency induction hardening technique of this tooth bar, adopt the inductor block of mid-frequency induction hardening lathe to be the suitable profiling inductor block of the teeth groove section form of shape and tooth bar, comprise the steps:
A, to link together back-to-back for two pieces tooth bar, make two pieces tooth bar form an entirety, and the tooth of two pieces tooth bar is symmetrically distributed in both sides; Be placed on mid-frequency induction hardening lathe by the two pieces tooth bar linked together, the facewidth direction of tooth bar is perpendicular to horizontal direction; In subsequent step, the corresponding teeth groove of the two pieces tooth bar linked together carries out synchronous processing;
B, the continuous induction heating of employing monodentate, inductor block moves from the bottom to top along facewidth direction, is heated the flank of tooth of tooth bar teeth groove and tooth root by inductor block simultaneously; After heating, in tooth bar heating zone apart from the temperature of surperficial 5mm depth be 750 ~ 950 DEG C, wherein, embodiment one is 750 ~ 760 DEG C apart from the temperature of surperficial 5mm depth, embodiment two is 850 ~ 860 DEG C apart from the temperature of surperficial 5mm depth, and embodiment three is 940 ~ 950 DEG C apart from the temperature of surperficial 5mm depth;
C, described mid-frequency induction hardening lathe are provided with the spray cooling device adjacent and servo-actuated with inductor block, and described spray cooling device is positioned at the below of inductor block; While implementation step B, pass into pressurized air to spray cooling device, compressed air temperature is 20 ~ 25 DEG C, pressure is 3 ~ 5bar, and speed of cooling is 2 ~ 10 DEG C/S; With the motion of inductor block, heating zone tooth bar being completed to heating is implemented air-cooled, and the temperature on surface, air-cooled rear tooth bar heating zone is 200 ~ 400 DEG C; After completing, close inductor block and stop to spray cooling device ventilation, inductor block from top to bottom to move reset along tooth bar teeth groove;
After D, thermograde within the scope of the depth of hardening zone on top layer, tooth bar heating zone are stable, inductor block moves from the bottom to top along rack tooth cross direction again, inductor block keeps closing, pass into AQ251 water-based quenching medium to spray equipment simultaneously, the concentration of medium of AQ251 water-based quenching medium is 9% ~ 11%, temperature is 24 DEG C ~ 32 DEG C, its cooling rate when 500-800 DEG C≤180 DEG C/sec, 200-400 DEG C time≤62 DEG C/sec, through the spray equipment servo-actuated with inductor block, continuous liquid cooling is implemented to tooth bar along facewidth direction, complete structural transformation;
The hard surfacing that B, step C and step D complete whole tooth bar is respectively repeated steps to each teeth groove of tooth bar.
After having quenched, the tooth bar of each embodiment all carries out low-temperaturetempering by existing technique to tooth bar, tempering temperature 180 DEG C, tempering time 24 hours.After tempering, two teeth are randomly drawed to the tooth bar of each embodiment and has carried out stressed condition detection, all in compressive stress state, specifically as shown in table 2; Detect the hardness of each embodiment, as shown in table 3, the effective depth of hardening of each embodiment is as shown in table 4 simultaneously.
The stressed condition of table 2, embodiment
The hardness of table 3, embodiment
The effective depth of hardening of table 4, embodiment
In addition to the implementation, applicant has also been two groups of comparative examples for above-described embodiment, and comparative example, compared with above-described embodiment, only adopts the different types of cooling, and the setting of other parameters except the type of cooling is all identical.First group of comparative example, adopts the technique described in paper in background technology, adopts spray equipment to implement liquid cooling after induction heating immediately, and the sample of this comparative example is after quenching terminates, and tooth bar root finds naked eyes visible crack.Second group of comparative example, two cover spray equipments are connected below inductor block, logical pressurized air in the spray equipment of inductor block, another spray equipment leads to cooling fluid, also namely after induction heating, air-cooled and liquid cooling is implemented successively immediately, implement liquid cooling after stable without the need to the thermograde within the scope of the depth of hardening zone on top layer, tooth bar heating zone, the sample of this comparative example, after quenching terminates, finds naked eyes visible crack at tooth bar root equally.
Technique of the present invention, the induction quenching of foundry goods super-modulus tooth bar as described embodiments can be applicable to, therefore, inevitable, also can be applicable to the forging super-modulus tooth bar induction quenching that structure property is better than foundry goods super-modulus tooth bar, also namely can be applicable to the induction quenching of all kinds of super-modulus tooth bar.
Claims (10)
1. modulus is in the mid-frequency induction hardening technique of the heavily loaded tooth bar of 50mm≤m≤150mm, adopt the inductor block of mid-frequency induction hardening lathe to be the suitable profiling inductor block of the teeth groove section form of shape and tooth bar, comprise the steps:
A, tooth bar is placed on mid-frequency induction hardening lathe;
B, heated the flank of tooth of tooth bar teeth groove and tooth root by inductor block, tooth bar heating zone, after completing heating, all reaches quenching temperature within the scope of the depth of hardening zone on top layer, tooth bar heating zone simultaneously;
C, tooth bar is completed heating heating zone implement air-cooled, air-cooled rate of cooling is greater than critical cooling rate, and air-cooled rear tooth bar heating zone surface temperature is between martensite start temperature and martensite finish transition temperature;
D, tooth bar complete air-cooled after, and through conduction of heat, after the thermograde within the scope of the depth of hardening zone on top layer, tooth bar heating zone is stable, implement liquid cooling to heating zone, complete structural transformation, the rate of cooling of liquid cooling is greater than critical cooling rate.
2. modulus as claimed in claim 1 is in the mid-frequency induction hardening technique of the heavily loaded tooth bar of 50mm≤m≤150mm, and it is characterized in that: in described step B, adopt continuous induction heating, inductor block is along the continuous induction heating of facewidth direction exercise.
3. modulus as claimed in claim 2 is in the mid-frequency induction hardening technique of the heavily loaded tooth bar of 50mm≤m≤150mm, it is characterized in that: in described step B, adopt the continuous induction heating of monodentate, only the wall scroll teeth groove of tooth bar is heated at every turn, the heating that B completes whole tooth bar is respectively repeated steps to each teeth groove of tooth bar.
4. modulus as claimed in claim 3 is in the mid-frequency induction hardening technique of the heavily loaded tooth bar of 50mm≤m≤150mm, it is characterized in that: described mid-frequency induction hardening lathe is provided with the spray cooling device adjacent and servo-actuated with inductor block; In described step C, to spray cooling device ventilation, implement continuously air-cooled along moving of facewidth direction to tooth bar heating zone with inductor block; In described step D, pass into cooling fluid to spray cooling device, along moving of facewidth direction continuous liquid cooling is implemented to tooth bar heating zone with inductor block; The hard surfacing that B, step C and step D complete whole tooth bar is respectively repeated steps to each teeth groove of tooth bar.
5. modulus as claimed in claim 4 is in the mid-frequency induction hardening technique of the heavily loaded tooth bar of 50mm≤m≤150mm, it is characterized in that: described spray cooling device is positioned at the below of inductor block, in described steps A, when placing tooth bar, the facewidth direction of tooth bar is perpendicular to horizontal direction, in step B, step C and step D, inductor block all moves from the bottom to top along facewidth direction.
6. modulus as claimed in claim 4 is in the mid-frequency induction hardening technique of the heavily loaded tooth bar of 50mm≤m≤150mm, it is characterized in that: ventilate to spray cooling device while implementing heating through inductor block, with the motion of inductor block, synchronous completing steps B and step C; Complete heating and air-cooled after, close inductor block and stop to spray cooling device ventilate, then pass into cooling fluid to spray cooling device, with the motion completing steps D of inductor block.
7. the modulus as described in claim 1,2,3,4,5 or 6 is in the mid-frequency induction hardening technique of the heavily loaded tooth bar of 50mm≤m≤150mm, it is characterized in that: link together back-to-back for two pieces tooth bar, make two pieces tooth bar form an entirety, and the tooth of two pieces tooth bar is symmetrically distributed in both sides; In step the two pieces tooth bar linked together is placed on mid-frequency induction hardening lathe, in the subsequent step of steps A, synchronous processing is carried out to the corresponding teeth groove of the two pieces tooth bar linked together.
8. the modulus as described in claim 1,2,3,4,5 or 6, in the mid-frequency induction hardening technique of the heavily loaded tooth bar of 50mm≤m≤150mm, is characterized in that: described tooth bar adopts CrNiMo cast steel material to make.
9. modulus as claimed in claim 8 is in the mid-frequency induction hardening technique of the heavily loaded tooth bar of 50mm≤m≤150mm, it is characterized in that: described tooth bar adopts G35CrNiMo6-6 material to make; In step B, after requiring heating, it is 750 ~ 950 DEG C in the temperature at depth of hardening zone place, tooth bar heating zone; In step C, the temperature of air-cooled rear rack surface is 200 ~ 400 DEG C.
10. modulus as claimed in claim 9 is in the mid-frequency induction hardening technique of the heavily loaded tooth bar of 50mm≤m≤150mm, it is characterized in that: in described step C, pass into pressurized air to spray cooling device; In described step D, pass into water-based quenching medium to spray cooling device.
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| CN113774278B (en) * | 2021-08-20 | 2022-06-10 | 中信重工机械股份有限公司 | Novel water-quenched cast steel heavy-duty gear material and preparation method thereof |
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Effective date of registration: 20180315 Address after: 618013 Deyang Pearl River West Road, Sichuan, No. 460 Patentee after: Double (Deyang) heavy equipment Co., Ltd. Address before: 618013 Deyang Pearl River West Road, Sichuan, No. 460 Patentee before: Erzhong Group (Deyang) Heavy Equipment Co., Ltd. |