Method for processing zirconium alloy shaft of mother liquor circulating pump

Abstract

The application discloses a mother liquor circulating pump zirconium alloy shaft machining method, and belongs to the field of machining, and solves the low machining precision of the zirconium alloy shaft in the prior art. The method comprises the following steps: hot forging a zirconium alloy bar to obtain a blank, removing the black skin of the blank and performing ultrasonic detection. The blank is coarsely turned to obtain a workpiece. After the coarse turning, the workpiece is annealed in a vacuum furnace. After the annealing treatment, the workpiece is subjected to ultrasonic detection. The workpiece is semi-finely turned and subjected to ultrasonic detection. The semi-finely turned workpiece is coarsely ground, and the center hole is lapped. After the coarse grinding, threads with key grooves are turned on the workpiece. The key grooves are milled on the workpiece, and the workpiece is subjected to penetration detection after the milling of the key grooves. The workpiece is subjected to stress relief annealing in a vacuum furnace after the penetration detection. The workpiece is finely ground after the stress relief annealing, and the center hole is lapped. Threads are turned on the workpiece after the fine grinding. The workpiece is subjected to pre-oxidation treatment after the thread turning. The application guarantees the machining precision of the zirconium alloy shaft.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mechanical processing, in particular to a mother liquor circulating pump zirconium alloy shaft processing method. BACKGROUND

[0002] The pump shaft is an important part of the mother liquor circulating pump, which supports and drives the impeller to rotate at high speed, so the torsional strength and surface roughness of the pump shaft not only need to meet the requirements, but also the coaxiality, runout and other tolerances need to meet the requirements. At the same time, since the mother liquor circulating pump is not fully enclosed, the pump shaft is in a corrosive working condition for a long time, so the corrosion resistance of the pump shaft is also relatively high.

[0003] Zirconium and zirconium alloy have excellent corrosion resistance to various acids, alkalis and salts, and have become an important manufacturing material for chemical and petroleum chemical industry equipment. At present, the pump shaft of the mother liquor circulating pump is also generally processed by zirconium alloy. However, due to the high viscosity of zirconium alloy, it is difficult to control the shape and position tolerance and surface roughness during zirconium alloy shaft processing. SUMMARY

[0004] The embodiment of the present application provides a mother liquor circulating pump zirconium alloy shaft processing method, which solves the problem of low processing precision of the zirconium alloy shaft in the prior art.

[0005] The embodiment of the present application provides a mother liquor circulating pump zirconium alloy shaft processing method, which solves the problem of low processing precision of the zirconium alloy shaft in the prior art.

[0006] The zirconium alloy bar is hot forged into a blank, the black skin of the blank is removed and ultrasonic detection is performed;

[0007] The blank that passes the ultrasonic detection of rough turning is obtained as a workpiece;

[0008] After rough turning, the workpiece is annealed in a vacuum furnace;

[0009] After the annealing treatment is completed, the workpiece is subjected to ultrasonic detection;

[0010] The workpiece that passes the ultrasonic detection of semi-finish turning;

[0011] The workpiece after semi-finish turning is rough ground with a margin, and the center hole is lapped;

[0012] After rough grinding, the workpiece is turned with key groove threads on both ends;

[0013] The key groove is milled on the workpiece, and after the key groove is milled, the workpiece is subjected to penetration detection;

[0014] The workpiece that passes the penetration detection is subjected to stress relief annealing in a vacuum furnace;

[0015] After the stress relief annealing is completed, the workpiece is finely ground, and the center hole is lapped.

[0016] threading on the workpiece after fine grinding;

[0017] pre-oxidation treatment on the workpiece after threading.

[0018] In a possible implementation, the workpiece is annealed in a vacuum furnace after rough threading, and specifically comprises:

[0019] the workpiece is vertically hung in a vacuum furnace with a vacuum degree of ≤0.04 Pa after rough threading;

[0020] the workpiece is annealed at a temperature of 700-750°C for 2 hours;

[0021] the furnace is cooled to below 100°C, and the workpiece is taken out and air-cooled.

[0022] In a possible implementation, the workpiece is vertically hung in a vacuum furnace with a vacuum degree of ≤0.04 Pa after rough threading, and specifically comprises:

[0023] the workpiece is vertically hung in a pit-type vacuum furnace with a vacuum degree of ≤0.04 Pa after rough threading and annealed for 2 hours.

[0024] In a possible implementation, the workpiece that passes the penetration detection is annealed in a vacuum furnace, and specifically comprises:

[0025] the workpiece that passes the penetration detection is vertically hung in a vacuum furnace with a vacuum degree of ≤0.04 Pa;

[0026] the workpiece is annealed at a temperature of 540-590°C for 1-3 hours;

[0027] the furnace is cooled to below 100°C, and the workpiece is taken out and air-cooled.

[0028] In a possible implementation, when the workpiece is fine ground, the selected abrasive wheel material is green silicon carbide, the green silicon carbide has a particle size of 60 mesh, a hardness grade of J, an organization number of 7, and a ceramic binder.

[0029] In a possible implementation, the workpiece is fine ground and the center hole is lapped after the stress relief annealing, and specifically comprises:

[0030] the workpiece is fine ground at both ends of the outer circle and the two shaft shoulder end faces after the stress relief annealing;

[0031] the workpiece is fine ground at both ends of the outer circle and the two shaft shoulder end faces after the stress relief annealing;

[0032] Finishing the workpiece at a rotating speed of 35mm / min and a feeding amount of 0.01mm.

[0033] In a possible implementation, when rough turning the blank, the rake angle γ0 is between 8°-13°, the relief angle α0 is between 16°-17°, the main offset angle K r is between 42°-48°, the inclination angle λ is between 2°-6°, and the nose radius γ ε =0.5mm-1mm.

[0034] In a possible implementation, when semi-finishing turning the workpiece, the rake angle γ0 is between 5°-7°, the relief angle α0 is between 16°-17°, the main offset angle K r is between 27°-33°, the inclination angle λ is 0°, and the nose radius γ ε =0.5mm-1mm.

[0035] In a possible implementation, after the thread turning is finished, the workpiece is pre-oxidized, and the pre-oxidation process specifically includes:

[0036] After the thread turning is finished, the workpiece is vertically hung in a resistance furnace.

[0037] The temperature is increased in steps, and when the temperature is increased to each whole hundred temperature, the temperature is kept at the whole hundred temperature for 30min, until the temperature is increased to 400℃ and kept for 3 hours.

[0038] The furnace is cooled to 100℃, and the workpiece is taken out and air-cooled.

[0039] In a possible implementation, the temperature is increased in steps, and the increasing in steps specifically includes:

[0040] The temperature is increased from the furnace temperature at a temperature increasing rate of 50℃ / h-150℃ / h.

[0041] The one or more technical solutions provided in the embodiments of the application have at least the following technical effects or advantages:

[0042] The embodiment of the present application provides a mother liquor circulating pump zirconium alloy shaft machining method, which comprises the following steps: hot forging a zirconium alloy bar to obtain a blank, removing the black skin of the blank and performing ultrasonic detection. The blank is coarsely turned to obtain a workpiece. After the coarse turning, the workpiece is annealed in a vacuum furnace. After the annealing, the workpiece is ultrasonically detected. The workpiece is semi-finely turned and ultrasonically detected. The workpiece is coarsely ground with a margin after the semi-fine turning, and the center hole is lapped. After the coarse grinding, the workpiece is turned to have key groove threads on both ends. The workpiece is milled to have key grooves, and then the workpiece is penetrant tested. The workpiece is stress relieved in a vacuum furnace after the penetrant test. The workpiece is finely ground and the center hole is lapped. The workpiece is turned to have threads. The workpiece is pre-oxidized after the thread turning. The present application is aimed at the properties and cutting characteristics of zirconium alloy, and the above machining method is used to ensure the shape tolerance, surface roughness, machining strength and corrosion resistance of the zirconium alloy shaft, so as to ensure the machining precision of the zirconium alloy shaft and batch production of the zirconium alloy shaft. On the basis of ensuring that the material mechanical properties meet the use requirements, the zirconium alloy shaft without defects, stable size, high size and position tolerance precision, good surface roughness, high surface hardness, wear resistance and corrosion resistance is machined. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the description of the embodiments of the present application will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0044] Figure 1 The flowchart of the mother liquor circulating pump zirconium alloy shaft machining method provided by the embodiment of the present application is shown in the figure.

[0045] Figure 2 The structure schematic diagram of the blank provided by the embodiment of the present application is shown in the figure.

[0046] Figure 3 The structure schematic diagram of the zirconium alloy shaft provided by the embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0048] In the description of the embodiments of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. The terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance. In addition, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0049] Please refer to Figure 1 The mother liquor circulating pump zirconium alloy shaft processing method provided by the embodiments of the present application comprises steps 101-112:

[0050] Step 101: hot forging of zirconium alloy bar stock to obtain a blank, remove the black skin of the blank and perform ultrasonic testing. Among them, the zirconium alloy bar stock is selected by secondary ingot. In actual application, by performing ultrasonic testing on the blank, internal defects of the blank can be found to ensure the processing strength of the zirconium alloy at the source.

[0051] Step 102: rough turning of the ultrasonic testing qualified blank to obtain a workpiece. Specifically, the ultrasonic testing qualified blank is supported by a center support, each outer circle, step allowance, root R, and the blank is center drilled.

[0052] Among them, when rough turning the blank, the rake angle γ0 is between 8°-13°, the relief angle α0 is between 16°-17°, the main offset angle K r is between 42°-48°, the blade inclination angle λ is between 2°-6°, and the tool tip arc radius γ ε =0.5mm-1mm. In actual application, according to the cutting characteristics of zirconium alloy, in order to reduce the cutting deformation and cutting temperature of zirconium alloy and ensure sufficient heat dissipation, the rake angle γ0 is between 8°-13° when rough turning. Since the elastic modulus of zirconium alloy is small and the cold hardening phenomenon is serious, the relief angle α0 is between 16°-17° when rough turning. In order to avoid scratching the machined surface during cutting, the blade inclination angle λ is between 2°-6° when rough turning. In order to prevent tool tip cracking and wear, the tool tip arc radius γ ε =0.5mm-1mm when rough turning.

[0053] Specifically, since the zirconium alloy has the characteristics of high strength and hardness, large plastic deformation resistance, serious cold hardening phenomenon, small thermal conductivity and high chemical activity, the material of the tool is required to have the characteristics of high hardness, high strength, good wear resistance and heat resistance, so the rough turning tool material YG8 is selected. In addition, since the ignition point of zirconium alloy is relatively low, dry cutting of zirconium alloy is strictly prohibited during cutting process, so cutting with extreme pressure emulsion with large thermal conductivity, large specific heat and large vaporization heat is adopted during cutting process, and the cutting fluid is fully, quickly and large-flow poured during cutting process to ensure the best high-pressure cooling effect.

[0054] Step 103: After rough turning, the workpiece is annealed in a vacuum furnace. The vacuum furnace is a specific space in which the vacuum system is used to discharge part of the material in the furnace cavity, so that the pressure in the furnace cavity is less than one standard atmosphere, so that the space in the furnace cavity realizes the vacuum state. Further, the workpiece is annealed in the vacuum furnace to avoid the reaction of zirconium with oxygen in the air.

[0055] Specifically, step 103 includes steps 1031-1033:

[0056] Step 1031: After rough turning, the workpiece is vertically hung in a vacuum furnace with a vacuum degree of ≤0.04 Pa. In actual application, the workpiece is vertically hung in the vacuum furnace to avoid deformation of the workpiece during heat treatment.

[0057] Further, after rough turning, the workpiece is vertically hung in a vacuum furnace with a vacuum degree of ≤0.04 Pa, which specifically includes:

[0058] After rough turning, the workpiece is vertically hung in a vacuum furnace with a vacuum degree of ≤0.04 Pa for annealing treatment for 2 hours. The pit type vacuum furnace has the advantages of simple equipment device, no environmental pollution and good process repeatability.

[0059] Step 1032: Annealing treatment of the workpiece at a temperature of 700-750℃ for 2 hours.

[0060] Step 1033: Slowly cool to below 100℃, and take out the furnace for air cooling. In practice, by annealing the workpiece, the workpiece can meet the requirements of tensile strength ≥485MPa and yield strength ≥380MPa.

[0061] Step 104: After the annealing treatment is completed, the workpiece is subjected to ultrasonic detection. Specifically, after the annealing treatment is completed, the workpiece is subjected to ultrasonic detection, which can find the internal defects of the workpiece, so that the possible defects of the workpiece can be investigated.

[0062] Step 105: the semi-finish machining ultrasonic testing qualified workpiece. Specifically, the ultrasonic testing qualified workpiece is clamped at one end, the other end is topped, the middle is supported by a center support, each outer circle is semi-finished according to the required size, the single side allowance of the step is left, each relief groove is machined and the fillet is ensured.

[0063] Wherein, when the workpiece is semi-finished, the rake angle γ0 is between 5°-7°, the relief angle α0 is between 16°-17°, the main offset angle Kr is between 27°-33°, the blade inclination angle λ is 0°, and the tool nose radius γ ε =0.5mm-1mm. In actual application, according to the cutting characteristics of zirconium alloy, in order to reduce the cutting deformation and cutting temperature of zirconium alloy and ensure sufficient heat dissipation, the rake angle γ0 is between 5°-7° when semi-finished. Because the elastic modulus of zirconium alloy is small and the cold hardening phenomenon is serious, the relief angle α0 is between 16°-17° when semi-finished. In order to avoid scratching the machined surface during cutting, the blade inclination angle λ is 0° when semi-finished. In order to prevent tool tip cracking and wear, the tool nose radius γ ε =0.5mm-1mm when semi-finished.

[0064] Specifically, because zirconium alloy has the characteristics of high strength and hardness, large plastic deformation resistance, serious cold hardening phenomenon, small thermal conductivity and high chemical activity, the material of the tool is required to have high hardness, high strength, good wear resistance and heat resistance, etc., so the semi-finish tool material YG8 is selected.

[0065] Further, according to the cutting characteristics of zirconium alloy, the cutting speed, feed rate and cutting depth of zirconium alloy must be low during cutting, so the cutting parameters of zirconium alloy shaft are selected as shown in Table 1:

[0066] Table 1-Selection of cutting parameters

[0067]

[0068] Step 106: rough grinding each outer circle of the semi-finished workpiece with allowance, and repairing the center hole. Specifically, the semi-finished workpiece is installed with double top, each outer circle is rough ground with allowance, and the center hole is repaired during rough grinding.

[0069] Step 107: after rough grinding, the workpiece is machined with keyway thread at both ends. Specifically, the workpiece is clamped at one end, the other end is topped, the middle is supported by a center support, and the keyway thread at both ends is machined according to the required size.

[0070] Step 108: Milling the keyway on the workpiece, and performing the penetrant testing on the workpiece after the milling of the keyway. In practical application, after the milling of the keyway on the workpiece, the workpiece is installed with the double top center for milling the keyway, and the penetrant testing is performed on the workpiece after the milling of the keyway. Specifically, the penetrant testing is performed on the workpiece after the milling of the keyway, which can prevent the micro-cracks on the surface of the workpiece during the machining process. In addition, the milling of the keyway is arranged between the rough grinding and the finish grinding of the workpiece, which can better meet the coaxiality and the outer circle run-out requirements of the reference.

[0071] Step 109: The workpiece that passes the penetrant testing is subjected to the stress relief annealing treatment in the vacuum furnace.

[0072] Specifically, step 109 includes steps 1091-1093.

[0073] Step 1091: The workpiece that passes the penetrant testing is vertically hung in the vacuum furnace with a vacuum degree of ≤0.04 Pa. In practical application, the workpiece is vertically hung in the vacuum furnace to avoid the deformation of the workpiece during the heat treatment.

[0074] Step 1092: The workpiece is subjected to the stress relief annealing treatment at a temperature of 540-590℃ for 1-3 hours.

[0075] Step 1093: The workpiece is cooled to below 100℃ in the furnace and is taken out for air cooling. In practical application, the stress relief annealing treatment of the workpiece can prevent the zirconium alloy shaft from exceeding the tolerance due to the stress of the milling of the keyway, and can stabilize the size of the zirconium alloy shaft.

[0076] Step 110: The workpiece is finish ground after the stress relief annealing, and the center hole is lapped.

[0077] Specifically, when the workpiece is finish ground, the green silicon carbide with a particle size of 60 mesh, a hardness grade of J, an organization number of 7, and a ceramic binder is selected. Specifically, the green silicon carbide has the advantages of high hardness, strong cutting ability, stable chemical properties, and good heat conduction performance, and is therefore suitable for grinding the workpiece with high hardness.

[0078] Specifically, step 110 includes steps 1101-1102.

[0079] Step 1101: The workpiece is finish ground on the outer circle of each end and the end face of each shaft shoulder after the stress relief annealing.

[0080] Step 1102: The workpiece is turned over multiple times during the finish grinding of the workpiece to timely lap the center hole, and the center hole is lubricated with butter. In practical application, the center hole of the workpiece is timely lapped to ensure the grinding quality.

[0081] Step 1103: finishing the workpiece at a rotating speed of 35 mm / min and a feeding amount of 0.01 mm. Specifically, the surface roughness of the zirconium alloy shaft can be guaranteed to meet the requirement of Ra 1.6 um, and the outer circle run-out of the bearing part of the final shaft can be guaranteed to be 0.01-0.015.

[0082] Step 111: threading on the workpiece after the fine grinding;

[0083] Step 112: pre-oxidizing the workpiece after the threading. In actual application, the surface hardness of the zirconium alloy shaft and the corrosion resistance to acetic acid medium can be increased through the pre-oxidizing.

[0084] Specifically, the step 112 includes steps 1121-1123.

[0085] Step 1121: vertically hanging the workpiece in the resistance furnace after the threading. The resistance furnace is an industrial furnace which uses electric current to make the electric heating element or heating medium in the furnace generate heat, so as to heat the workpiece or material. Placing the zirconium alloy shaft in the resistance furnace for heating can make the zirconium alloy shaft well contact with the air, so as to realize the oxidation treatment of the zirconium alloy shaft. Through the heating of the resistance furnace and the oxidation of the surface of the zirconium alloy shaft by the oxygen element in the air, the oxidation of the zirconium alloy shaft can be realized without additional addition of oxygen during heating, which reduces the production cost and is suitable for industrial mass production. Moreover, since the oxygen content in the air is low, the zirconium alloy shaft can be heated for a longer time during the oxidation process, so that the texture of the oxidized zirconium coating is tighter and the quality is better. Due to the longer oxidation heating time, a thicker oxidized zirconium coating can also be obtained.

[0086] Step 1122: stepwise temperature rising, and when the temperature rises to each whole hundred temperature, the temperature at the whole hundred temperature is kept for 30 min, until the temperature rises to 400℃ and is kept for 3 hours. Specifically, through the stepwise temperature rising and the keeping at the whole hundred temperature, the temperature of the whole workpiece is uniformly raised, so that the zirconium alloy shaft produces a small and uniform deformation, which can control the final deformation amount of the zirconium alloy shaft.

[0087] Specifically, the stepwise temperature rising includes: rising the temperature from the furnace temperature at a temperature rising rate of 50℃ / h-150℃ / h.

[0088] Step 1123: cooling to 100℃ with the furnace and air cooling after taking out of the furnace. Through the repeated process of heating and keeping, the zirconium alloy shaft is heated more uniformly, and the deformation of the zirconium alloy shaft during heating is avoided.

[0089] This invention provides a method for machining a zirconium alloy shaft for a mother liquor circulation pump. The method includes: hot forging a zirconium alloy bar to obtain a blank; removing the black skin from the blank and performing ultrasonic testing; rough machining the ultrasonically tested blank to obtain a workpiece; annealing the workpiece in a vacuum furnace after rough machining; performing ultrasonic testing on the workpiece after annealing; semi-finish machining the ultrasonically tested workpiece; rough grinding the outer diameters of the semi-finish machined workpiece with a allowance, and finishing the center hole; machining threads with keyways at both ends on the workpiece after rough grinding; milling keyways on the workpiece, and performing penetrant testing on the workpiece after keyway milling; performing stress-relief annealing on the workpiece in a vacuum furnace after penetrant testing; finish grinding the workpiece after stress-relief annealing, and finishing the center hole; machining threads on the finish-ground workpiece; and pre-oxidizing the workpiece after thread machining. This invention addresses the properties and cutting characteristics of zirconium alloys. Through the aforementioned processing methods, it ensures the dimensional and positional tolerances and surface roughness of the zirconium alloy shaft. Three-stage defect detection eliminates potential defects in the zirconium alloy shaft. Annealing and stress-relief annealing ensure the machining strength of the zirconium alloy shaft. Pre-oxidation treatment guarantees the corrosion resistance requirements of the zirconium alloy shaft, thereby ensuring the machining accuracy of the zirconium alloy shaft and enabling mass production. This application, while ensuring that the material's mechanical properties meet the usage requirements, produces defect-free zirconium alloy shafts with stable dimensions, high dimensional and positional tolerances, good surface roughness, high surface hardness, and wear and corrosion resistance.

[0090] To more clearly illustrate the present invention, the following is an embodiment of a specific method for machining a zirconium alloy shaft for a mother liquor circulation pump:

[0091] The zirconium alloy bar is hot-forged into an asphalt blank. The chemical composition and mechanical properties of the blank should meet the requirements of ASTM B493. The black skin of the blank is removed and ultrasonic testing is performed according to NB / T 47013.3. The blank is qualified as Grade I.

[0092] The ultrasonically tested blank is supported by a center frame; the material is YG8, the front angle γ0 is 10°, the rear angle α0 is 16°, and the principal deviation angle K is... r The blade angle is 45°, the cutting edge inclination angle λ is 4°, and the tip radius γ is 45°. ε Rough turn each outer diameter with a 0.6mm tool, leaving a 4mm allowance on each side of the step, and R2-R3 at the root; drill a center hole in the blank.

[0093] After rough machining, the workpiece is vertically suspended in a pit-type vacuum furnace with a vacuum degree ≤0.04Pa; the workpiece is annealed at 730℃ for 2 hours; it is then cooled in the furnace to below 100℃ and air-cooled after being removed from the furnace.

[0094] After the annealing process, the workpiece was subjected to ultrasonic testing in accordance with NB / T 47013.3, and it passed Level I.

[0095] The ultrasonically tested and qualified workpiece is clamped at one end, supporting the other end, and supported in the middle by a central frame. The material is YG8, the front angle γ0 is 6°, the rear angle α0 is 17°, and the principal deviation angle K is... r The blade angle is 30°, the cutting edge inclination angle λ is 0°, and the tip radius γ is 0°. ε Using a 0.7mm tool, semi-finish turn each outer circle of the workpiece to the required dimensions, leaving a 0.7mm allowance on each side of the step, turn each relief groove and ensure the fillets (polished) and chamfers, and blunt the sharp angles.

[0096] After semi-finish turning, install the workpiece with double centers, rough grind each outer circle leaving a 0.4mm allowance, and repair the center hole during rough grinding.

[0097] Clamp one end of the workpiece, support the other end, and use a center frame in the middle to machine the keyway threads at both ends according to the required dimensions.

[0098] After machining the keyway threads at both ends, install the workpiece with double centers and mill the keyway. When milling the keyway, pay attention to leaving a grinding allowance on the outer circle. After milling the keyway, perform a penetrant test on the workpiece according to NB / T 47013.5. It is qualified as Level I.

[0099] The workpiece that passes the penetrant test is vertically suspended in a vacuum furnace with a vacuum degree ≤0.04Pa; the workpiece is subjected to stress-relief annealing at a temperature of 565℃ and held for 1 hour; it is then cooled in the furnace to below 100℃ and air-cooled after being removed from the furnace.

[0100] After stress-relief annealing, a grinding wheel made of green silicon carbide is used to finely grind the outer diameters at both ends of the workpiece and the end faces of the two shaft shoulders. The green silicon carbide has a particle size of 60 mesh, a hardness grade of J, a structure number of 7, and a ceramic binder. During the fine grinding process, the workpiece is turned around multiple times to grind the center hole in a timely manner, and grease is applied to lubricate the center hole. The workpiece is then finished with a rotation speed of 35 mm / min and a feed rate of 0.01 mm.

[0101] Threads are machined onto the workpiece after it has been finely ground.

[0102] After thread cutting is completed, the workpiece is vertically suspended in a pit-type resistance furnace; the temperature is increased from the furnace temperature at a rate of 50℃ / h, and when the temperature reaches each whole number of 100, it is held for 30 minutes at each whole number of 100 until it reaches 400℃ and is held for 3 hours; the workpiece is cooled to 100℃ in the furnace, and then removed from the furnace and air-cooled to obtain an oxide coating with a surface hardness of 600HV.

[0103] The various embodiments in this specification are described in a progressive manner. For the same or similar parts between the various embodiments, please refer to each other. Each embodiment focuses on describing the differences from other embodiments.

[0104] The above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some or all of the technical features thereof can be replaced by equivalents; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. A method of machining a mother liquor circulating pump zirconium alloy shaft, characterized by, The method comprises the following steps: a zirconium alloy bar is hot forged into a blank, the black skin of the blank is removed, and ultrasonic detection is performed; a workpiece is obtained by rough turning the blank that passes the ultrasonic detection; after the rough turning, the workpiece is annealed in a vacuum furnace; after the annealing, the workpiece is subjected to ultrasonic detection; the workpiece that passes the ultrasonic detection after the semi-finishing turning; the workpiece is rough ground and semi-finishing turned, and the center hole is lapped; after the rough grinding, a thread with a key groove is turned on the workpiece; a key groove is milled on the workpiece, and the workpiece is subjected to penetration detection after the key groove is milled; the workpiece that passes the penetration detection is subjected to stress relief annealing in a vacuum furnace; the workpiece is finish ground after the stress relief annealing, and the center hole is lapped; a thread is turned on the workpiece after the finish grinding; the workpiece is pre-oxidized after the thread turning; the workpiece is annealed in a vacuum furnace after the rough turning, and the annealing process specifically comprises the following steps: after the rough turning, the workpiece is vertically hung in a vacuum furnace with a vacuum degree of less than or equal to 0.04 Pa; the workpiece is annealed at a temperature of 700-750 ℃ for 2 hours; the workpiece is cooled to below 100 ℃ in the furnace and is air-cooled after being taken out of the furnace; the workpiece is finish ground after the stress relief annealing, and the center hole is lapped, and the process specifically comprises the following steps: after the stress relief annealing, the workpiece is finish ground on each outer circle of two ends and two shaft shoulder end faces; during the finish grinding of the workpiece, the workpiece is repeatedly turned over to timely lap the center hole, and butter is applied to lubricate the center hole; the workpiece is finished at a speed of 35 mm / min and a feed amount of 0.01 mm; during the rough turning of the blank, the rake angle γ0 is between 8° and 13°, the relief angle α0 is between 16° and 17°, the main offset angle Kr is between 42° and 48°, the blade inclination angle λ is between 2° and 6°, and the tool nose radius γE is 0.5 mm-1 mm; during the semi-finishing turning of the workpiece, the rake angle γ0 is between 5° and 7°, the relief angle α0 is between 16° and 17°, the main offset angle Kr is between 27° and 33°, the blade inclination angle λ is 0°, and the tool nose radius γE is 0.5 mm-1 mm.

2. The method of claim 1, wherein the mother liquor circulating pump zirconium alloy shaft is made of Zircaloy-2. after the rough turning, the workpiece is vertically hung in a vacuum furnace with a vacuum degree of less than or equal to 0.04 Pa, and the process specifically comprises the following steps: after the rough turning, the workpiece is vertically hung in a vacuum furnace with a vacuum degree of less than or equal to 0.04 Pa for annealing for 2 hours.

3. The method of claim 1, wherein the mother liquor circulating pump zirconium alloy shaft is made of Zircaloy-2. the workpiece that passes the penetration detection is subjected to stress relief annealing in a vacuum furnace, and the process specifically comprises the following steps: the workpiece that passes the penetration detection is vertically hung in a vacuum furnace with a vacuum degree of less than or equal to 0.04 Pa; the workpiece is subjected to stress relief annealing at a temperature of 540-590 ℃ for 1-3 hours; the workpiece is cooled to below 100 ℃ in the furnace and is air-cooled after being taken out of the furnace.

4. The method of claim 1, wherein the zirconium alloy shaft is a mother liquor circulating pump zirconium alloy shaft. during the finish grinding of the workpiece, green silicon carbide is selected as the grinding wheel material, the green silicon carbide has a particle size of 60 mesh, a hardness grade of J, a structure number of 7, and a binder of ceramic.

5. The method of claim 1, wherein the mother liquor circulating pump zirconium alloy shaft is made of Zircaloy-2. after the thread turning, the workpiece is pre-oxidized, and the process specifically comprises the following steps: after the thread turning, the workpiece is vertically hung in a resistance furnace; the temperature is increased in steps, and when the temperature is increased to each whole hundred temperature, the workpiece is kept at the whole hundred temperature for 30 minutes until the temperature is increased to 400 ℃ and kept for 3 hours; Cooling in the furnace to 100℃, and then air cooling after leaving the furnace.

6. The method of claim 5 wherein, The stepwise temperature rising specifically comprises: Rising from the furnace temperature at a temperature rising rate of 50℃ / h-150℃ / h.

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