Quenching method for local carburizing part and quenching hanging tool

Abstract

The invention discloses a quenching method for a local carburizing part and a quenching hanging tool, the local carburizing part is arranged to be of a thin-wall short sleeve structure with an opening in one end, a through hole is formed in the bottom of the other end, an annular boss is formed on the periphery of the through hole at the bottom end of the inner wall of the part, and the inner wall of a sleeve of the local carburizing part is a carburizing part; the quenching hanging tool comprises two iron wire rings used for hanging and an iron wire binding wire connected between the two iron wire rings. Wherein the iron wire binding wire sequentially penetrates through the through holes of the parts so as to bind the local carburized parts into a string at preset intervals, and when the parts are bound, the part, extending out of the uppermost part, of the iron wire binding wire forms an iron wire ring, and the part, extending out of the uppermost part, of the iron wire binding wire forms another iron wire ring; the upper end and the lower end of a string of bound parts are respectively provided with an iron wire ring for hanging a quenching hook, so that the string of bound parts are hung in a downward opening or upward opening manner and corresponding procedures are implemented by hanging the iron wire rings at different positions in different stages of the quenching process. According to the technical scheme, the problem that according to an existing quenching mode, no matter a binding mode with an upward opening or a downward opening is adopted for a local carburizing part, elliptical deformation can occur on the outer wall of the part, and consequently follow-up machining is difficult is solved.

Description

Technical Field

[0001] The invention relates to but is not limited to the technical field of heat treatment process, and in particular to a quenching method for local carburized parts and a quenching hanging tool. Background Art

[0002] A part of our company is a partially carburized part. After heat treatment, quenching and tempering, the hardness of the carburized part is 58-63HRC. Figure 1 The figure shows the structure of a partially carburized part to be quenched. The part is in the shape of a short sleeve, with an open structure at one end and an opening size of φ44.35. A small hole is opened at one end with a size of φ5.5. There is no carburized layer on the outer surface and bottom of the part, and the carburized part is on the inner wall of the sleeve (see Figure 1 Thick black line).

[0003] Currently targeting Figure 1 The quenching method of the parts shown is to tie and hang multiple parts in a direction with the opening facing upward or downward, immerse the parts in a salt bath furnace for insulation, and after hanging out of the salt bath furnace, immerse them in an alkaline bath in the same hanging direction for cooling and quenching; in the above quenching method, no matter whether the parts are tied with the opening facing upward or downward, the outer wall of the parts will have elliptical deformation, which makes subsequent machining more difficult. Summary of the invention

[0004] Purpose of the invention: In order to solve the above-mentioned technical problems, the embodiments of the present invention provide a quenching method and a quenching hanging tool for locally carburized parts, so as to solve the existing quenching method. Regardless of whether the locally carburized parts are tied with the opening facing upward or downward, the outer wall of the part will have an elliptical deformation, which will make subsequent machining more difficult.

[0005] Technical solution of the present invention: In the first aspect, the embodiment of the present invention provides a quenching hanging tool for partially carburized parts, wherein the partially carburized parts are arranged as a thin-walled short sleeve structure with an opening at one end, a through hole is opened at the bottom of the other end, and an annular boss is formed at the bottom of the inner wall of the part around the through hole, and the inner wall of the sleeve of the partially carburized parts is a carburized part; the quenching hanging tool comprises: two wire rings for hanging, and a wire binding wire connected between the two wire rings;

[0006] Among them, the wire binding line passes through the through holes of each part in turn to bind the locally carburized parts into a string at preset intervals, and when the parts are bound, the part of the wire binding line extending out of the uppermost part forms a wire ring, and the part of the wire binding line extending out of the uppermost part forms another wire ring, so that the upper and lower ends of the bound string of parts are respectively reserved with a wire ring for quenching hook hanging, so that at different stages of the quenching process, by hanging wire rings in different positions, the bound string of parts can be hung with the openings facing downward or upward and the corresponding processes can be carried out.

[0007] Optionally, in the quenching hanging tool for partially carburized parts as described above,

[0008] Each of the parts tied in a string is surrounded by iron wire, and the iron wire binding lines used for binding the parts have a binding knot formed at preset intervals, which is used to sample the iron wire and the binding knots surrounding each part to limit the binding position of each part on the quenching hanging tooling.

[0009] Optionally, in the quenching hanging tool for partially carburized parts as described above,

[0010] The interval between adjacent parts in the string of parts is ≥10mm.

[0011] Optionally, in the quenching hanging tool for partially carburized parts as described above,

[0012] The two wire rings in the quenching hanging tool are used to hang by selecting the wire ring on one side of the through-hole end of the part, so that a string of parts tied together are kept warm in the salt bath furnace in a hanging manner with the openings facing downward, and are also used to hang by selecting the wire ring on one side of the open end of the part, so that a string of parts tied together are immersed in alkali solution for cooling in a hanging manner with the openings facing upward.

[0013] In the second aspect, an embodiment of the present invention further provides a quenching and hanging method for locally carburized parts, which uses a quenching and hanging tool for locally carburized parts as described in any of the above items to perform the quenching and hanging method, and in different stages of the quenching and hanging method, by hanging wire rings at different positions, a string of parts to be tied together are hung with the openings facing downward or upward and the corresponding processes are carried out.

[0014] Optionally, in the quenching hanging method for partially carburized parts as described above, the method comprises:

[0015] Step 1: Use a quenching hanging tool to tie no more than 10 partially carburized parts into a string, with the adjacent parts spaced ≥10 mm apart; and when the parts are tied, reserve a wire ring at each end for quenching hook hanging;

[0016] Step 2, first hang the parts tied into a string on the quenching hook with the opening downward and immerse them in a salt bath furnace for insulation; the insulation temperature is 780℃±10℃, and the insulation time is 5-7min;

[0017] Step 3, after the insulation is completed, the parts tied into a string are hung out of the salt bath furnace in a hanging manner with the openings facing downward;

[0018] Step 4, take another quenching hook and hook the wire ring at the lower end of the part, so that the hanging direction of the part is changed from opening downward to opening upward, that is, the parts tied into a string are hung on the quenching hook in the way of opening upward hanging;

[0019] Step 5, immerse the parts tied into a string in an alkali tank with the openings facing upward and cool for more than 5 minutes;

[0020] Step 6, after cooling, take the parts tied into a string out of the alkali tank by hanging them with the openings facing upwards, and clean them in a hot water tank.

[0021] Step 7, place the parts in an oven at 200℃±30℃, keep warm for 2h30min-3h, and air cool.

[0022] Optionally, in the quenching hanging method for locally carburized parts as described above, in step 3, during the process of hanging the parts tied in a string out of the salt bath furnace in a downward hanging manner, the salt liquid evenly and quickly flushes the outer walls of each part, so that the parts are less deformed than in a hanging manner with the openings facing upward.

[0023] Optionally, in the quenching hanging method for locally carburized parts as described above, in step 5, the parts tied into a string are immersed in an alkali tank for cooling in a hanging manner with the openings facing upwards, and the thermal stress generated during the cooling process causes the outer wall to shrink, thereby generating compressive stress on the inner wall; while the inner wall of the part does not shrink due to the high post-cooling temperature, generating tensile stress on the outer wall; and in step 5, cooling in the alkali solution in a hanging manner with the openings facing upwards results in less deformation than cooling in a cooling manner with the openings facing downwards.

[0024] Beneficial effects of the present invention: The embodiments of the present invention provide a quenching method and a quenching hanging tool for partially carburized parts, which use a quenching hanging tool to tie the partially carburized parts, and the partially carburized parts are tied in a two-way hanging and tying form before quenching, that is, when the partially carburized parts are tied, a wire ring is reserved at the upper and lower ends for hanging by the quenching hook, so that the partially carburized parts can be hung with the opening upward or with the opening downward. On the one hand, when the partially carburized parts are kept warm in the salt bath furnace, the parts are hung with the opening downward, such as Figure 4 As shown, the above process adopts Figure 4In the hanging form shown, when the parts are hung out after the insulation is completed, the salt liquid evenly and quickly washes over the outer wall of the parts, and the deformation of the parts is small.

[0025] On the other hand, after the part is lifted out of the salt bath furnace, use another quenching hook to hook the wire ring at the lower end of the part opening so that the part opening is hung upwards. Figure 5 Then the part is hung with the opening upward and immersed in the alkali solution, using Figure 5 The part is suspended with the opening upwards and immersed in the alkali solution, and the outer wall of the part is cooled first. Since the base of the part is 10A steel, thermal stress is generated during the cooling process, the outer wall shrinks, and compressive stress is generated on the inner wall. However, the inner wall does not shrink due to the high post-cooling temperature, and tensile stress is generated on the outer wall. When the alkali solution is immersed in the inner wall of the part to cool, the inner wall undergoes a martensitic transformation and generates tissue stress. The tissue stress continues to apply tensile stress to the outer wall to eliminate the compressive stress generated on the outer wall. Since the outer wall of the part is cooled first, the outer wall has basically cooled to the alkali solution temperature and the yield strength has been restored. The remaining tissue stress cannot squeeze the outer wall to deform, causing the part to deform into the hole. Since part of the tissue stress is offset, the amount of deformation into the hole is small, which does not affect the machining of the next step. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0027] Figure 1 It is a schematic diagram of the structure of a partially carburized part to be subjected to a quenching process;

[0028] Figure 2 For Figure 1 A schematic diagram of a binding method for a conventional quenching method of a partially carburized part is shown;

[0029] Figure 3 For Figure 1 A schematic diagram of a binding method for a conventional quenching method of a partially carburized part is shown;

[0030] Figure 4 A schematic diagram of a hanging method for a partially carburized part during quenching provided by an embodiment of the present invention;

[0031] Figure 5 A schematic diagram of another hanging method for the quenching process of a partially carburized part provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention more clear, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other arbitrarily without conflict.

[0033] As described in the above background technology, Figure 1 The part shown in the figure is a part that needs to be quenched. The base material of the part to be quenched is low carbon steel 10A, the carbon content of the carburized part is 0.8%, which belongs to the range of high carbon steel, and the thickness of the carburized layer is 0.6mm-0.9mm. In view of the high carbon content on the inner wall surface of the part, the part is quenched by heating and heat preservation in a salt bath furnace, and then quenched and cooled in an alkaline bath after the insulation, and finally tempered in an oven. The existing quenching method uses a binding method with the opening facing up or the opening facing down for the part that is locally carburized, and the outer wall of the part will have the problem of elliptical deformation. The existing quenching method and its existing problems are described in detail below.

[0034] The current quenching methods include: 1. Tie no more than 10 parts into a string, with the parts spaced ≥10mm apart, with the opening of the parts facing upward, i.e. the wire of the quenching hook is tied above the opening, such as Figure 2 As shown, for Figure 1 The schematic diagram of the binding of a conventional quenching method for a partially carburized part is shown. Figure 2 The binding method shown is with the parts opening upward; 2. Immerse a string of parts hanging on the quenching hook in a salt bath furnace, with a holding temperature of 780℃±10℃ and a holding time of 5-7min; 3. After the holding is completed, lift the parts from the salt bath furnace and immerse them in an alkali bath in the same hanging direction for cooling and quenching, with the alkali solution temperature of 170℃-180℃; 4. After the parts are cooled in the alkali solution for 5min, they are immersed in water for cooling and cleaning. 5. Finally, the parts are kept in an oven at 200℃±30℃ for 2h30min-3h, and air-cooled.

[0035] After quenching using the above operation method, the outer wall of the part will have an elliptical deformation, and subsequent machining is difficult. The reason for this deformation is that after the part is kept warm in the salt bath furnace, the elliptical deformation occurs when the part is lifted out of the salt bath furnace; the yield strength of the part decreases after being heated to the quenching temperature of 780℃±10℃ and kept warm for 5-7min, and the plastic deformation increases, that is, the part is softer. In addition, there is a step with a height of 4.5mm and a diameter of 14mm in the middle of the bottom of the part, and there is a hole with a diameter of 5.5mm in the center of the step, which is relatively small. When the part is lifted up from the salt bath furnace with the opening upward, the salt liquid flows out slowly at the bottom of the part due to the small hole at the step, and there is no hole at the bottom of the circle outside the step, so the salt liquid cannot flow out. Therefore, in the process of lifting the part out of the salt bath furnace, the salt liquid cannot be discharged from the bottom, and an outward force is continuously generated to support the inner wall of the part. The outer wall of the part is thin, with a thickness of 2.82mm in one part and 3.65mm in another part. The part is soft at 780℃±10℃, which causes the part to deform into an elliptical shape. The main reason for the deformation is that the part is impacted by the physical force of the salt solution in the high temperature and soft state.

[0036] against Figure 2 The problem with the quenching solution shown above is that the current treatment method considers tying the parts with the opening downward and hanging them in a salt bath furnace for insulation, such as Figure 3 As shown, for Figure 1 The schematic diagram of the binding of a conventional quenching method for a partially carburized part is shown. Figure 3 The binding method shown is that the opening of the part is downward. When the part is lifted out after the insulation is completed, the salt liquid evenly and quickly washes over the outer wall of the part, and the deformation of the part is small; then the part is immersed in the alkali solution with the opening downward for cooling and quenching, and the part still undergoes elliptical deformation. The reason for the elliptical deformation in this quenching method is mainly caused by the thermal stress and tissue stress of the part during cooling; specifically, since the base material of the part is 10A steel, which is a low-carbon steel without the effect of quenching and strengthening, when the opening of the part is cooled downward, the carburized layer on the inner wall of the part and the 10A steel matrix are cooled at the same time. The carbon content of 10A steel is between 0.07% and 0.13%. When cooled at 780℃, thermal stress deformation is mainly generated; that is, as the 10A steel is cooled, according to the principle of thermal expansion and contraction, the outer wall of the part begins to shrink as the temperature drops, generating compressive stress to the inner wall; and since the carbon content of the carburized layer on the inner wall of the part is about 0.8%, it belongs to high-carbon steel, and the cooling process mainly transforms austenite into martensite structure to generate tissue stress. When the temperature of the inner wall of the part drops, it begins to transform from austenite to martensite, and the volume increases, generating tensile stress on the outer wall. The tensile stress caused by the increase in the volume of martensite on the inner wall of the part is greater than the thermal stress generated from the outer wall to the inner wall. In addition, there is no martensite transformation on the outer wall of 10A steel, the temperature is high, and the hardness and strength are low. Under the action of organizational stress, it deforms outward and produces an elliptical deformation.

[0037] In order to solve the above problems, an embodiment of the present invention provides a quenching method for a partially carburized part and a quenching hanging tool, so as to prevent the sleeve-shaped partially carburized part from undergoing elliptical deformation after quenching and tempering.

[0038] The present invention provides the following specific embodiments which can be combined with each other. The same or similar concepts or processes may not be described in detail in some embodiments.

[0039] The embodiment of the present invention provides a quenching method and a quenching hanging tool for a partially carburized part. The quenching method mainly considers two principles:

[0040] First, the force principle of parts hanging upwards out of the salt bath furnace;

[0041] Second, the deformation principle caused by the thermal stress and structural stress generated by steels with different carbon contents during the cooling process.

[0042] Based on the above two principles, a quenching method for locally carburized parts and a quenching hanging tool are proposed in an embodiment of the present invention. The application of the above two principles in the quenching method is specifically described in the following embodiment.

[0043] Part 1: The embodiment of the present invention provides a quenching and hanging tool for implementing a quenching and hanging method for partially carburized parts, for Figure 1 The partially carburized part shown, that is, the partially carburized part is arranged as a thin-walled short sleeve structure with an opening at one end, a through hole is opened at the bottom of the other end, and an annular boss is formed at the bottom end of the inner wall of the part around the through hole, and the inner wall of the sleeve of the partially carburized part is a carburized part, and the carbon content of the carburized part is, for example, 0.8%, which belongs to the high carbon steel range.

[0044] like Figure 4 As shown, it is a schematic diagram of a hanging method for the quenching process of a local carburized part provided by an embodiment of the present invention; Figure 5 , which is a schematic diagram of another hanging method for the quenching process of a locally carburized part provided by an embodiment of the present invention.

[0045] Reference Figure 4 and Figure 5 As shown, the quenching hanging tool provided in the embodiment of the present invention includes: two wire rings for hanging, and a wire binding wire connected between the two wire rings.

[0046] By adopting the quenching hanging tool, the wire binding line passes through the through holes of each part in turn, and the partially carburized parts are bundled into a string at preset intervals. When the parts are bundled, the part of the wire binding line extending out of the uppermost part forms a wire ring, and the part of the wire binding line extending out of the uppermost part forms another wire ring, so that a wire ring for quenching hook hanging is reserved at the upper and lower ends of the bundled string of parts respectively, so that at different stages of the quenching process, by hanging the wire rings in different positions, the bundled string of parts can be hung with the openings facing downward or upward and the corresponding processes can be carried out.

[0047] like Figure 4 and Figure 5 As shown, when the quenching hanging tool provided by the embodiment of the present invention is used to tie parts, each part tied in a string is surrounded by iron wire, and the iron wire binding line used to tie the parts has a binding knot formed at a preset interval, which is used to sample the iron wire and the binding knot surrounding each part to limit the binding position of each part on the quenching hanging tool.

[0048] In one embodiment, the interval between adjacent parts in a string of parts is ≥10 mm.

[0049] In specific implementation, the functions of the two wire rings in the quenching hanging tool are as follows: on the one hand, by selecting the wire ring on one side of the through-hole end of the part for hanging, a string of parts tied together are kept warm in the salt bath furnace in a hanging manner with the opening facing downward; on the other hand, by selecting the wire ring on one side of the open end of the part for hanging, a string of parts tied together are immersed in the alkali solution in a hanging manner with the opening facing upward for cooling.

[0050] Part Two: Based on the quenching and hanging tool for locally carburized parts provided by the above-mentioned embodiments of the present invention, an embodiment of the present invention further provides a quenching and hanging method for locally carburized parts, which specifically uses the quenching and hanging tool for locally carburized parts provided by any of the above-mentioned embodiments to perform the quenching and hanging method, and in different stages of performing the quenching and hanging method, by hanging wire rings at different positions, a string of parts to be tied together are hung with the openings facing downward or upward and the corresponding processes are performed.

[0051] In a specific implementation, the quenching method for a partially carburized part provided in an embodiment of the present invention comprises the following steps:

[0052] Step 1: Use the quenching hanging tool to tie no more than 10 partially carburized parts into a string, with the interval between adjacent parts ≥10mm. When tying the parts, reserve a wire ring at the upper and lower ends for hanging by the quenching hook.

[0053] Step 2: first hang the parts tied together in a string on the quenching hook with the opening facing downward and immerse them in a salt bath furnace for heat preservation; Figure 4 Hanging method shown.

[0054] The holding temperature in this step is 780°C ± 10°C, and the holding time is 5-7 minutes.

[0055] Step 3, after the insulation is completed, the parts tied into a string are hung out of the salt bath furnace in a hanging manner with the openings facing downward.

[0056] During the lifting process of the parts in this step, since the openings of the parts are tied downward and lifted out, the salt solution can evenly and quickly flush the outer walls of the parts, resulting in less deformation of the parts.

[0057] Step 4: Take another quenching hook and hook the wire ring at the bottom of the part to change the hanging direction of the part from opening downward to opening upward. That is, hang the parts tied into a string on the quenching hook with the opening upward. Figure 5 shown.

[0058] Step 5: immerse the parts tied into a string in an alkali tank with the openings facing upward and cool for more than 5 minutes.

[0059] Step 6, after cooling, take the parts tied into a string out of the alkali tank by hanging them with the openings facing upwards, and clean them in a hot water tank.

[0060] Step 7, place the parts in an oven at 200℃±30℃, keep warm for 2h30min-3h, and air cool.

[0061] In the embodiment of the present invention, Figure 1 The local carburized parts with the specific structure shown in the figure did not show elliptical deformation after the quenching method described above. Small shrinkage deformation appeared on the inner wall of the part, which was generally 0.02mm to 0.04mm, and did not affect the subsequent machining.

[0062] The quenching method and quenching hanging tool for partially carburized parts provided in the embodiment of the present invention use the quenching hanging tool to tie the partially carburized parts, and the partially carburized parts are tied in a two-way hanging and tying form before quenching, that is, when the partially carburized parts are tied, a wire ring is reserved at the upper and lower ends for hanging by the quenching hook, so that the partially carburized parts can be hung with the opening upward or with the opening downward. On the one hand, when the partially carburized parts are kept warm in the salt bath furnace, the parts are hung with the opening downward, such as Figure 4 As shown, the above process adopts Figure 4 In the hanging form shown, when the parts are hung out after the insulation is completed, the salt liquid evenly and quickly washes over the outer wall of the parts, and the deformation of the parts is small.

[0063] On the other hand, after the part is lifted out of the salt bath furnace, use another quenching hook to hook the wire ring at the lower end of the part opening so that the part opening is hung upwards. Figure 5Then the part is hung with the opening upward and immersed in the alkali solution, using Figure 5 The part is suspended with the opening upwards and immersed in the alkali solution, and the outer wall of the part is cooled first. Since the base of the part is 10A steel, the thermal stress generated during the cooling process causes the outer wall to shrink, generating compressive stress on the inner wall; and the inner wall does not shrink due to the high post-cooling temperature, generating tensile stress on the outer wall. When the alkali solution is immersed in the inner wall of the part to cool, the inner wall undergoes a martensitic transformation to generate tissue stress, and the tissue stress continues to apply tensile stress to the outer wall to eliminate the compressive stress generated on the outer wall. Since the outer wall of the part is cooled first, the outer wall has basically cooled to the alkali temperature and the yield strength has been restored. The remaining tissue stress cannot squeeze the outer wall to deform, causing the part to deform into the hole. Since part of the tissue stress is offset, the amount of deformation into the hole is small, which does not affect the machining of the next step.

[0064] Although the embodiments disclosed in the present invention are as above, the contents are only embodiments adopted to facilitate understanding of the present invention and are not intended to limit the present invention. Any technician in the field to which the present invention belongs can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A quenching hanging tool for locally carburized parts, characterized in that: The partially carburized part is configured as a thin-walled short sleeve structure with an opening at one end, a through hole at the bottom of the other end, and an annular boss is formed at the bottom of the inner wall of the part around the through hole, and the inner wall of the sleeve of the partially carburized part is a carburized part; the quenching hanging tooling includes: two wire rings for hanging, and a wire binding wire connected between the two wire rings; Among them, the wire binding line passes through the through holes of each part in turn to bind the locally carburized parts into a string at preset intervals, and when the parts are bound, the part of the wire binding line extending out of the uppermost part forms a wire ring, and the part of the wire binding line extending out of the uppermost part forms another wire ring, so that the upper and lower ends of the bound string of parts are respectively reserved with a wire ring for quenching hook hanging, so that at different stages of the quenching process, by hanging wire rings in different positions, the bound string of parts can be hung with the openings facing downward or upward and the corresponding processes can be carried out.

2. The quenching hanging tool for partially carburized parts according to claim 1, characterized in that: Each of the parts tied in a string is surrounded by iron wire, and the iron wire binding lines used for binding the parts have a binding knot formed at preset intervals, which is used to sample the iron wire and the binding knots surrounding each part to limit the binding position of each part on the quenching hanging tooling.

3. The quenching hanging tool for partially carburized parts according to claim 2, characterized in that: The interval between adjacent parts in the string of parts is ≥10mm.

4. The quenching hanging tool for partially carburized parts according to any one of claims 1 to 3, characterized in that: The two wire rings in the quenching hanging tool are used to hang by selecting the wire ring on one side of the through-hole end of the part, so that a string of parts tied together are kept warm in the salt bath furnace in a hanging manner with the openings facing downward, and are also used to hang by selecting the wire ring on one side of the open end of the part, so that a string of parts tied together are immersed in alkali solution for cooling in a hanging manner with the openings facing upward.

5. A quenching and hanging method for locally carburized parts, characterized in that: A quenching hanging method is performed using a quenching hanging tool for locally carburized parts as described in any one of claims 1 to 4, and in different stages of the quenching hanging method, wire rings are hung at different positions so that a string of tied parts are hung with the openings facing downward or upward and the corresponding processes are performed.

6. The quenching and hanging method for partially carburized parts according to claim 5, characterized in that: The method comprises: Step 1: Use a quenching hanging tool to tie no more than 10 partially carburized parts into a string, with the adjacent parts spaced ≥10 mm apart; and when the parts are tied, reserve a wire ring at each end for quenching hook hanging; Step 2, first hang the parts tied into a string on the quenching hook with the opening downward and immerse them in a salt bath furnace for insulation; the insulation temperature is 780℃±10℃, and the insulation time is 5-7min; Step 3, after the insulation is completed, the parts tied into a string are hung out of the salt bath furnace in a hanging manner with the openings facing downward; Step 4, take another quenching hook and hook the wire ring at the lower end of the part, so that the hanging direction of the part is changed from opening downward to opening upward, that is, the parts tied into a string are hung on the quenching hook in the way of opening upward hanging; Step 5, immerse the parts tied into a string in an alkali tank with the openings facing upward and cool for more than 5 minutes; Step 6, after cooling, take the parts tied into a string out of the alkali tank by hanging them with the openings facing upwards, and clean them in a hot water tank. Step 7, place the parts in an oven at 200℃±30℃, keep warm for 2h30min-3h, and air cool.

7. The quenching and hanging method for partially carburized parts according to claim 6, characterized in that: In step 3, when the parts tied into a string are hung out of the salt bath furnace in a downward hanging manner, the salt liquid evenly and quickly washes over the outer walls of each part, so that the parts are less deformed than in a binding manner with the openings upward.

8. The quenching and hanging method for partially carburized parts according to claim 6, characterized in that: In step 5, the parts tied into a string are immersed in an alkali tank in a hanging manner with the openings facing upwards for cooling. The thermal stress generated during the cooling process causes the outer wall to shrink, generating compressive stress on the inner wall. However, the inner wall of the parts does not shrink due to the high post-cooling temperature, generating tensile stress on the outer wall. Compared with the cooling method with the opening facing downwards, cooling in the alkali solution in step 5 in a hanging manner with the openings facing upwards results in less deformation.

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