CN114438288B - Material defect gear quenching method - Google Patents
Material defect gear quenching method Download PDFInfo
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- CN114438288B CN114438288B CN202210037752.XA CN202210037752A CN114438288B CN 114438288 B CN114438288 B CN 114438288B CN 202210037752 A CN202210037752 A CN 202210037752A CN 114438288 B CN114438288 B CN 114438288B
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- 238000010791 quenching Methods 0.000 title claims abstract description 136
- 230000000171 quenching effect Effects 0.000 title claims abstract description 134
- 239000000463 material Substances 0.000 title claims abstract description 82
- 230000007547 defect Effects 0.000 title claims abstract description 62
- 238000000034 method Methods 0.000 title claims abstract description 40
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 38
- 239000007788 liquid Substances 0.000 claims abstract description 31
- 238000010438 heat treatment Methods 0.000 claims abstract description 23
- 238000005496 tempering Methods 0.000 claims abstract description 21
- 238000007599 discharging Methods 0.000 claims abstract description 16
- 230000002950 deficient Effects 0.000 claims description 16
- 230000003137 locomotive effect Effects 0.000 claims description 2
- 238000012797 qualification Methods 0.000 abstract description 7
- 229910000734 martensite Inorganic materials 0.000 abstract description 6
- 238000012545 processing Methods 0.000 description 13
- 238000005255 carburizing Methods 0.000 description 5
- 238000001816 cooling Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 230000008520 organization Effects 0.000 description 3
- 238000005336 cracking Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/32—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for gear wheels, worm wheels, or the like
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
Abstract
The invention provides a material defect gear quenching method. The method comprises the following steps: a quenching step, a primary tempering step and a secondary tempering step, wherein the material defect gear is sequentially heated to 775-785 ℃ and kept at the temperature for 0.5-1 h, and kept at the temperature of 820-830 ℃ for 1-2 h, and the material defect gear is placed into water-based quenching liquid for quenching treatment after being discharged from a furnace to obtain a quenched gear; heating the quenched gear to 175-185 ℃ and preserving heat for 5-10 hours, and discharging to obtain a primary tempered gear; and heating the primary tempered gear to 185-195 ℃ and preserving heat for 5-10 hours, and discharging to obtain the secondary tempered gear. Based on the method, the material defect gear can be promoted to obtain more hidden needle martensite structures, and meanwhile, the diameter size and the common normal size of the material defect gear can be greatly improved, the endangered material defect gear product is converted into a qualified gear product, and the gear product qualification rate is further improved.
Description
Technical Field
The invention relates to the technical field of gear heat treatment, in particular to a material defect gear quenching method.
Background
The heavy-duty locomotive gear is made of 18CrNiMo7-6, most of the prior art adopts a carburizing and quenching heat treatment process to strengthen the surface of the gear, in the process, some endangered material defect gears are usually produced, the material defect gears cannot meet the metallographic structure requirement of the material (namely, more than 90% of hidden needle martensite is obtained), the shrinkage deformation is inconsistent after quenching, particularly, the diameter size is smaller (less than or equal to 978 mm), and the subsequent processing requirement (the diameter size of the gear is more than or equal to 978.2mm and the common normal size is more than or equal to 333.5 mm) cannot be met. If the above-mentioned material defect gear that is imminent to discard can not be handled properly, can lead to the overall disability rate of gear higher, the qualification rate is lower, can reach 85% at most. However, there is no method of treating the above-mentioned endangered defective gears. Therefore, it is necessary to provide a heat treatment method, which can treat the endangered material defect gear, so that the metallographic structure performance and the processing performance of the endangered material defect gear are improved, and particularly the diameter size of the gear is increased, so that the subsequent processing requirements can be met, and the qualification rate of the product in the production process is improved.
Disclosure of Invention
The invention mainly aims to provide a quenching method for a material defect gear, which aims to solve the problem that the material defect gear cannot be effectively treated in the prior art.
In order to achieve the above object, according to one aspect of the present invention, there is provided a material defective gear quenching method comprising: and (3) quenching: heating the gear with the defect material to 775-785 ℃ in sequence, preserving heat for 0.5-1 h, preserving heat for 1-2 h at 820-830 ℃, discharging the gear, and placing the gear into water-based quenching liquid for quenching treatment to obtain a quenched gear; and (3) primary tempering: heating the quenched gear to 175-185 ℃ and preserving heat for 5-10 hours, and discharging to obtain a primary tempered gear; and (3) a secondary tempering step: heating the primary tempered gear to 185-195 ℃ and preserving heat for 5-10 hours, and discharging to obtain the secondary tempered gear.
Further, the mass concentration of the quenching medium in the water-based quenching liquid is 10-20%.
Further, in the quenching treatment process, the treatment time is controlled to be 3-10 min.
Further, in the water-based quenching liquid, the quenching medium is PAG.
Further, the material defect gear is quenched in a quenching tank which is filled with water-based quenching liquid, and the material defect gear is arranged in the quenching tank in the following manner: providing a plurality of material defect gears; providing a lifting appliance, enabling the lifting appliance to penetrate through shaft holes of all material defect gears, enabling the material defect gears to be lifted in a quenching tank in a mutually parallel mode and immersed in water-based quenching liquid; a support assembly is disposed between each of the material defect gears.
Further, the support assembly comprises an annular connecting rod, and first support parts and second support parts which are fixed on the annular connecting rod at intervals, wherein one or more first support parts are arranged, one or more second support parts are arranged, at least one first support part is provided with a limiting structure, and the limiting structure is used for fixing a material defect gear on the support assembly.
Further, the lifting appliance comprises a fixing part and a lifting part connected with the fixing part, the fixing part is fixedly arranged outside the quenching tank, the lifting part penetrates through the shaft holes of the material defect gears to lift the material defect gears, and the height of the lifting part is adjustable.
Further, the diameter size of the secondary tempering gear is more than or equal to 978.2mm, and the common normal size is more than or equal to 333.5mm.
The inventor of the invention creatively discovers that the defective gear made of the material is heated to 775-785 ℃ in sequence, kept for 0.5-1 h, kept for 1-2 h at 820-830 ℃, discharged from the furnace and placed into water-based quenching liquid for quenching treatment. Correspondingly and synergistically, after the quenching step, the material is subjected to a primary tempering step and a secondary tempering step with specific technological parameters in sequence, so that the material defective gear can be promoted to obtain more hidden needle martensitic structure, and meanwhile, the diameter size and common normal size of the material defective gear can be greatly improved, and the endangered material defective gear product is converted into a qualified gear product, so that the qualification rate of the gear product is further improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:
FIG. 1 shows a schematic heat treatment of an embodiment of the present invention;
FIG. 2 is a schematic view showing the arrangement of a material defect gear in a furnace according to an embodiment of the present invention;
FIG. 3 shows a metallographic photograph of a pitch circle 20mm from the front end of a gear tooth in one embodiment of the invention;
FIG. 4 shows a metallographic photograph of the structure of the tooth root at the front end of the tooth in one embodiment of the invention;
FIG. 5 shows a metallographic view of the front end core of a gear tooth in accordance with one embodiment of the present invention;
FIG. 6 shows a metallographic view of the surface structure of a tip pitch circle in a gear tooth according to one embodiment of the invention;
FIG. 7 shows a metallographic photograph of the root structure of the middle end of a gear tooth in one embodiment of the invention;
FIG. 8 shows a metallographic view of a tooth center portion structure in one embodiment of the invention;
FIG. 9 is a schematic view of the support assembly of the arrangement of FIG. 2;
Fig. 10 shows schematic views of the front, middle, root, pitch and core of the gear teeth of fig. 3, 4, 5, 6, 7 and 8.
Wherein the above figures include the following reference numerals:
10. A material defect gear; 20. a lifting appliance; 30. a support assembly; 31. an annular connecting rod; 32. a first support portion; 33. a second supporting part;
A. a front end; B. a middle end; p, tooth direction; a. a pitch circle; b. a tooth root; c. a core.
Detailed Description
It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The application will be described in detail below with reference to the drawings in connection with embodiments.
As described in the background art, in the prior art, when 18CrNiMo7-6 heavy-duty gears are subjected to carburizing and quenching (oil-based quenching medium) heat treatment, some endangered material defect gears inevitably occur, and the material defect gears cannot meet the metallographic structure requirement of the materials (namely, more than 90% of hidden needle martensite is obtained), and the diameter size is smaller (less than or equal to 978 mm), so that the subsequent processing requirement cannot be met. In general, the person skilled in the art cannot grasp the rule of swelling and shrinking of such a rejected gear, and therefore cannot seek a suitable method to handle it effectively. While the present inventors, in the face of such a material defective gear, creatively proposed for the first time a material defective gear quenching method, as shown in fig. 1, which includes: a quenching step, a primary tempering step and a secondary tempering step, wherein the material defect gear is sequentially heated to 775-785 ℃ and kept at the temperature for 0.5-1 h, and kept at the temperature of 820-830 ℃ for 1-2 h, and the material defect gear is placed into water-based quenching liquid for quenching treatment after being discharged from a furnace to obtain a quenched gear; heating the quenched gear to 175-185 ℃ and preserving heat for 5-10 hours, and discharging to obtain a primary tempered gear; and heating the primary tempered gear to 185-195 ℃ and preserving heat for 5-10 hours, and discharging to obtain the secondary tempered gear.
Based on the cooperative coordination among the steps, the method can promote the material defect gear to obtain more hidden needle martensitic structure so as to meet the metallographic structure requirement of the material. Meanwhile, the diameter size and common normal size of the material defect gear can be greatly improved, the endangered scrapped gear product is converted into a qualified gear product, and the qualification rate of the gear product is further improved. In a word, through the cooperation of the specific water-based quenching and the two steps of the secondary tempering which are sequentially carried out, the gear with the defect of being scrapped can be converted into the qualified gear with the hidden needle martensitic structure of more than 95%, the diameter size expansion of the gear is more than or equal to 0.5, and the subsequent processing requirements can be better met, so that waste is changed into valuable, and the qualification rate of gear products can be greatly increased from 85% to 95%.
Additionally, the carburizing and quenching (oil-based quenching medium) heat treatment of the invention is a conventional technology process in the field, for example, when an oil-based quenching medium is adopted, the quenching process can be as follows: the gear after carburization is heated to 775-785 ℃ and kept for 0.5-1 h, 820-830 ℃ and kept for 1-2 h, and after the gear is discharged from the furnace, the gear is placed into oil-based quenching liquid for quenching treatment, and then the gear after quenching treatment is heated to 175-185 ℃ and kept for 5-10 h for tempering. The quenching medium in the oil-based quenching treatment process can be a conventional oil-based medium in the field such as quick bright quenching oil, and the quenching treatment time can be 55-65 min.
It should be noted that, before the above-mentioned material defect gear is subjected to the water-based quenching treatment of the present invention, it has been subjected to at least one oil-based quenching treatment during the conventional carburizing and quenching heat treatment, and the water-based quenching treatment involved in the quenching method of the present invention is the second quenching or the third quenching of the above-mentioned material defect gear.
In one embodiment of the invention, the mass concentration of the water-based quenching liquid is 10-20%. In order to further balance the above excellent properties of gears, it is preferable that the mass concentration of the water-based quenching liquid is 12 to 16%. Based on the above, the quenching effect of the gear is better, the diameter expansion of the gear is better, and the processing performance of the gear is better. Conversely, if the mass concentration of the water-based quench liquid exceeds 16%, the gear swell is slightly insufficient and the diameter size may still be difficult to meet the subsequent processing requirements. If the mass concentration is less than 12%, quenching cracks may occur in the gear.
In one embodiment of the present invention, the treatment time in the water-based quenching liquid is controlled to be 3 to 10 minutes. In order to further balance the stability and quenching effect of the gear in the quenching process, the treatment time of the quenched gear in the water-based quenching liquid after being discharged from the furnace is preferably controlled to be 5-8 min. Based on this, the gear diameter size expansion amount is promoted to be higher, and quenching cracks are not generated. If the treatment time is less than 5 minutes, the gear structure is not sufficiently transformed, the expansion is slightly insufficient, and the diameter size may still be difficult to meet the subsequent processing requirements. If the treatment time is longer than 8 minutes, quenching cracks may occur in the gear.
In a preferred embodiment, the material defect gear is subjected to quenching treatment in a quenching tank, wherein the quenching tank contains water-based quenching liquid, and as shown in fig. 2, the material defect gear is arranged in the quenching tank in the following manner: providing a plurality of material defect gears 10; providing a lifting appliance 20, enabling the lifting appliance to penetrate through shaft holes of all the material defect gears, so that the material defect gears are lifted in a quenching tank in a mutually parallel mode and immersed in water-based quenching liquid; a support assembly 30 is disposed between each of the material defect gears, respectively. As shown in fig. 9, the support assembly includes an annular connecting rod 31, and first and second support portions 32 and 33 fixed on the annular connecting rod at intervals, the first support portion is one or more, the second support portion is one or more, and at least one first support portion has a limit structure for fixing a material defect gear on the support assembly. And the height of the connecting rod is lower than that of the first supporting part and the second supporting part.
Specifically, when the gear is quenched, the gear with the material defects is suspended in a quenching tank in a mutually parallel manner and immersed in the water-based quenching liquid, so that the circulation of the water-based quenching medium can be more facilitated, the contact area between the central part of the gear and the quenching medium is increased, the quenching efficiency and the quenching effect can be further improved, and the product performance is promoted to be better. A supporting component is arranged between the gear and comprises a first supporting portion and a second supporting portion which are arranged at intervals, and the first supporting portion is provided with a limiting structure. Therefore, the gear can be stably fixed on the supporting component, so that the quenching stability is improved, and the gear can be fully quenched without cracking. The defective gear is heated in a well-type carburizing and quenching furnace (or may be a secondary furnace or more, and specific reference is made to GB/T9452-2012), and cooled in a quenching tank.
In a more preferred embodiment, the support assembly includes first and second support portions 32 and 33 fixed to the annular connecting rod at one-to-one intervals, and each of the first support portions has a limiting structure to make the material defect gear more stably fixed to the support assembly. Based on this, the stability of the material defective gear in the water-based quenching treatment can be further improved, and the amount of thermal deformation of the gear at the time of quenching can be reduced. Therefore, the gear has stronger adaptability in quenching treatment, the quenching stability can be further improved, the product cracks are reduced, and meanwhile, the mechanical property and the metallographic structure of the product are better. Moreover, based on the setting mode, the invention can process a plurality of gears at the same time, and the processing efficiency is higher.
Additionally, the person skilled in the art generally does not want to adopt water-based quenching liquid for quenching when quenching the 18CrNiMo7-6 heavy-duty gear, and the phenomena of poor material stability and easy occurrence of cracks of the gear can exist due to the large cooling intensity. In the quenching setting mode of the cooperative coordination, the gear can be more effectively prevented from cracking, and the excellent performance of the gear product can be further improved on the basis of better quenching stability.
In a preferred embodiment, the lifting appliance comprises a fixing part and a lifting part connected with the fixing part, wherein the fixing part is fixedly arranged outside the quenching tank, the lifting part penetrates through shaft holes of the material defect gears to lift the material defect gears, and the height of the lifting part is adjustable. Based on this, when a plurality of abandoned gears quenching treatment, adjustable hoist and mount portion height to every gear can both be higher efficient obtain the performance improvement.
In a preferred embodiment, the depth of the hardened layer of the gear after the treatment according to the present invention can reach 2.0 to 2.5mm and the hardness can reach 58 to 64HRC based on the above treatment method. In particular, the diameter size is more than or equal to 978.2mm, the common normal size is more than or equal to 333.5mm, and the subsequent processing requirements can be better met.
The application is described in further detail below in connection with specific examples which are not to be construed as limiting the scope of the application as claimed.
Example 1
1) The gear with the defects is heated to 780 ℃ and kept at the temperature of 50min and 825 ℃ for 80min in sequence, the gear is put into water-based quenching liquid in a quenching tank for quenching for 7min according to the arrangement mode of fig. 2 after being discharged from a furnace, and then the product is cleaned. Wherein the mass concentration of the quenching medium (PAG) in the water-based quenching liquid is 13 percent.
2) Tempering the quenched material for the first time: heating to 180 ℃, preserving heat for 480min, discharging, cooling to room temperature in air, and tempering the materials for the second time: heating to 190 ℃, preserving heat for 480min, discharging, and cooling to room temperature in air to obtain the product.
Example 2
The only difference from example 1 is that:
in the step 1), the process parameter of heat preservation at 825 ℃ for 80min is adjusted to 820 ℃ for 2h.
Example 3
The only difference from example 1 is that:
In the step 1), the process parameter of heat preservation at 825 ℃ for 80min is adjusted to be 830 ℃ for 1h.
Example 4
The only difference from example 1 is that:
In the step 1), the process parameter of quenching for 7min is adjusted to 6min.
Example 5
The only difference from example 1 is that:
In the step 1), the process parameter of quenching for 7min is adjusted to 8min.
Example 6
The only difference from example 1 is that:
In the step 2), the technological parameter of primary tempering is adjusted as follows: heating to 175 ℃, preserving heat for 10h, and discharging.
Example 7
The only difference from example 1 is that:
in the step 2), the technological parameter of primary tempering is adjusted as follows: heating to 185 ℃ and preserving heat for 5 hours, and discharging.
Example 8
The only difference from example 1 is that:
In the step 2), the process parameter of the secondary tempering is adjusted as follows: heating to 185 ℃ and preserving heat for 10h, and discharging.
Example 9
The only difference from example 1 is that:
In the step 2), the process parameter of the secondary tempering is adjusted as follows: heating to 195 ℃, preserving heat for 5 hours, and discharging.
Example 10
The only difference from example 1 is that:
In step 1), the process parameter of the mass concentration of the quenching medium (PAG) in the water-based quenching liquid is adjusted to 12%.
Example 11
The only difference from example 1 is that:
in step 1), the process parameter of the mass concentration of the quenching medium (PAG) in the water-based quenching liquid is adjusted to 16%.
Example 12
The only difference from example 1 is that:
In the step 1), the process parameter of quenching for 7min is adjusted to 15min. The gear develops quench cracks.
Example 13
The only difference from example 1 is that:
In step 1), the process parameter of the mass concentration of the quenching medium (PAG) in the water-based quenching liquid is adjusted to 20%.
Characterization of the properties:
Metallographic examination was carried out on the gear subjected to secondary tempering in example 1, and the metallographic examination photograph thereof is as follows: wherein, FIG. 3 is a pitch circle organization at a position 20mm from the front end of the gear teeth; FIG. 4 is a tooth tip tooth root tissue; FIG. 5 is a tooth tip core organization; FIG. 6 is a tooth tip pitch surface texture; FIG. 7 is a tooth center tooth root structure; fig. 8 is a tooth center portion organization. From the above figures, it can be seen that the gear after the secondary tempering of the present invention meets the technical quality specification TB/T2254. Fig. 10 shows schematic diagrams of the front end (a), the middle end (B), the pitch circle (a), the tooth root (B) and the core (c) of the gear teeth involved in the tooth direction (P), fig. 3, fig. 4, fig. 5, fig. 6, fig. 7 and fig. 8, wherein α and λ are specifically described in ISO6336-5 and GB3480.5 as "core measurement positions: the depth (lambda) in the normal direction of the 30 DEG (alpha) tangent line of the tooth width middle part from the tooth root is 5 times the depth of the hardened layer, but not less than 1 time the modulus.
Specific data for the geometry measurements of the article of example 1 (16 material defect gear samples were selected) are shown in table 1.
TABLE 1
Note that: the diameter dimensions in table 1 include the gear transverse direction diameter dimension and the longitudinal direction diameter dimension, and the common normal line dimension includes the gear transverse direction common normal line dimension and the longitudinal direction common normal line dimension. The transverse direction and the longitudinal direction take the center point of the gear as an intersection point, and are mutually perpendicular to form a cross shape through the intersection point.
Specific data for the geometric measurements of the articles of examples 2 to 13 (1 material defective gear sample each) are shown in table 2:
TABLE 2
Note that: the diameter dimensions in table 2 are the average of the transverse diameter dimensions and the longitudinal diameter dimensions of the gears, and the common normal dimension is the average of the transverse common normal dimensions and the longitudinal common normal dimensions of the gears.
From the above example data, it is found that the processing performance of the defective gear can be effectively improved by subjecting the material defective gear to the water-based quenching treatment, and in particular, the processing performance of the defective gear can be further effectively improved when the mass concentration of the water-based quenching liquid is 12 to 16% and the quenching time is 5 to 8 minutes. A water-based quench fluid having a mass concentration above the above range and/or a quench time below the above range may result in a slightly insufficient gear swell, and a diameter size that is still difficult to meet subsequent processing requirements. If the mass concentration of the water-based quenching liquid is lower than the above range and/or the quenching time is higher than the above range, quenching cracks may occur in the gear, and the gear cannot be effectively utilized.
In summary, the core innovation point of the invention is based on the following points:
1. And a water-based quenching liquid is adopted to quench the material defect gear.
2. The mass concentration of the water-based quenching liquid is 12-16%.
3. The water-based quenching treatment time is 5-8 min.
The technical scheme of the invention has the beneficial effects that: the gear with a large number of defects of the endangered scrapped materials is saved (the diameter of the common gear is in a shrinking trend after carburization, the expansion amount of the gear after oil-based quenching does not reach the expected target value), and the qualification rate of the finished product of the gear is improved from the original 85% to 95%.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. A method for quenching a material-defective gear, the method comprising:
And (3) quenching: sequentially heating the material defect gear to 775-785 ℃ and preserving heat for 0.5-1 h, and preserving heat for 1-2 h at 820-830 ℃, discharging the material defect gear, and then placing the material defect gear into a water-based quenching liquid for quenching treatment to obtain a quenched gear;
and (3) primary tempering: heating the quenched gear to 175-185 ℃ and preserving heat for 5-10 hours, and discharging to obtain a primary tempered gear;
and (3) a secondary tempering step: heating the primary tempered gear to 185-195 ℃ and preserving heat for 5-10 hours, and discharging to obtain a secondary tempered gear;
wherein, in the water-based quenching liquid, the quenching medium is PAG, and the mass concentration is 12-16%;
the material defect gear is an 18CrNiMo7-6 heavy-duty locomotive gear which is carburized and quenched by adopting an oil-based quenching medium.
2. The method for quenching a gear with a material defect according to claim 1, wherein the quenching treatment is performed for 3-10 min.
3. The method for quenching a material-defective gear according to claim 1 or 2, wherein the material-defective gear is subjected to the quenching treatment in a quenching tank in which the water-based quenching liquid is contained, and the material-defective gear is disposed in the quenching tank in such a manner that:
Providing a plurality of said material defect gears;
Providing a lifting appliance, and enabling the lifting appliance to penetrate through shaft holes of all the material defect gears, so that the material defect gears are lifted in the quenching tank in a mutually parallel mode and immersed in the water-based quenching liquid; a support assembly is disposed between each of the material defect gears.
4. A method of quenching a material defective gear according to claim 3 wherein the support assembly includes an annular connecting rod and first and second support portions fixed to the annular connecting rod at intervals, the first support portion being one or more, the second support portion being one or more, and at least one of the first support portions having a limit structure for securing the material defective gear to the support assembly.
5. The method for quenching a gear made of a material according to claim 4, wherein the hanger comprises a fixing portion and a hanging portion connected to the fixing portion, the fixing portion is fixedly arranged outside the quenching tank, the hanging portion is used for hanging the gear made of the material through shaft holes of the gears made of the material, and the height of the hanging portion is adjustable.
6. The method for quenching a gear with material defects according to claim 1 or 2, wherein the diameter size of the secondary tempered gear is not less than 978.2mm and the common normal size is not less than 333.5mm.
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