Heat treatment methods for different heat treatment workpieces in a vacuum furnace

Abstract

The present invention discloses a heat treatment method for completing different heat treatment workpieces in a vacuum furnace. The method has strong operability and can improve the processing efficiency of the heat treatment workpieces in subsequent processing. This method is achieved through the following technical solutions: first, a variable combined heat treatment tool for loading shaft heat treatment parts in a vacuum furnace is prepared, and each tool support body unit is symmetrical to two partition blocks through the guide rail groove on the inclined surface of the wedge-shaped moving block. The guide rod is positioned on the inclined surface of the isosceles middle block through the core shaft embedded in the center of the inner bevel gear through the guide hole. The bevel gear in the transmission shaft engages the inner bevel gear on the end of the guide rod to form a V-shaped cross angle structure in which the two-axis movement of the guide rod and the two-wing trapezoidal slider support the workpiece; the transmission shaft is rotated to drive the inner bevel gear of the guide rod to rotate, driving the trapezoidal slider to move obliquely along the specified direction of the wedge-shaped moving block guide groove and move to both sides along the specified guide rail inclined surface, so as to meet the ability of completing heat treatment of different workpieces in the same vacuum heat treatment furnace.

Description

Technical Field

[0001] The present invention belongs to the field of heat treatment, and specifically relates to a heat treatment method for completing different heat treatment workpieces in a vacuum furnace for manufacturing technology of key heat treatment workpieces such as aviation equipment shafts, thin-walled cylinders and special-shaped structures. Background Art

[0002] Landing gear heat treatment workpieces in the aviation manufacturing industry primarily include critical heat-treated parts such as shafts, thin-walled cylinders, and special-shaped structures. Their service life directly impacts the lifespan of the entire aircraft landing gear system. These critical heat-treated parts are the backbone of the landing gear. Currently, high-pressure gas quenching in China generally results in significant deformation of workpieces. Large, complex workpieces are prone to deformation and even cracking when subjected to continuous, rapid cooling from high temperatures. To prevent post-processing warping, cemented carbide generally requires heat treatment and tempering. Tempering reduces tool strength while increasing the carbide's plasticity and toughness. Heat treatment production is essential for fixtures and fixtures. However, various types of heating furnace fixtures, trays, baskets, and racks must be heated along with the workpiece. The heat they remove can sometimes equal or exceed the workpiece's heat, accounting for approximately 18% to 29% of the total heat, significantly increasing heat treatment production costs. Heat treatment operations are conducted at high temperatures, requiring the use of various auxiliary fixtures to facilitate workpiece loading and unloading, quenching, and transfer. Various auxiliary tooling is crucial for ensuring smooth heat treatment production, workpiece quality, and safe heat treatment operations. To this end, a variety of tooling is required, tailored to different furnace types, workpiece structures, and process requirements. Furthermore, for heat treatment of small quantities of sporadic workpieces, heat treatment technicians or workers often need to improvise simple tooling based on their production experience and practical circumstances. The workpieces are loaded into the furnace and remain relatively stationary throughout the heat treatment process. Loading and unloading workpieces requires manual labor from heat treatment workers, who utilize a variety of hand tools, such as draw hooks, push rods, rods, and forks. Shafts, for example, require various shims to straighten warped workpieces. Thin discs and sheet-shaped workpieces, which may have distorted during quenching, require fixtures to hold them in place during tempering. Workpiece quenching also requires the use of hanging baskets, mesh baskets, and hangers. Pit-type furnaces consume the most heat energy, followed by box-type and conveyor-belt furnaces. Conveyor-belt furnaces have long conveyor belts, and the subsequent cooling and reheating after heating results in significant ineffective heat loss. In addition, for workpieces with complex structures and small quantities, heat treatment workers are often required to fabricate tooling on-site to complete the heat treatment of the workpieces. Heat treatment of shaft-type workpieces must be carried out in a pit furnace with appropriate hanging tooling. However, detailed information and standards are currently not available in China for the available hanging process head shaft diameters. Vacuum heat treatment technology uses heating, cooling, vacuum, and other techniques to control the phase transformation, microstructure, and residual stresses of key heat treatment workpieces, thereby imparting performance or extreme performance to these workpieces. Therefore, vacuum heat treatment technology is a key technology for achieving long life, high reliability, and structural weight reduction for key basic heat treatment workpieces. Vacuum heat treatment of key heat treatment workpieces not only ensures the required structure, mechanical properties, and process performance, but also unlocks the potential of these workpieces, ensuring and improving their quality and lifespan, and maximizing the potential of the material.Heat treatment fixtures are consumable parts. Their primary failure mode is high-temperature oxidation thinning, which significantly reduces their strength. Welding and casting are commonly used to manufacture heat treatment fixtures. Controlling the material and manufacturing costs of fixtures is crucial for controlling heat treatment production costs. High-temperature strength requires the fixtures holding the workpieces to withstand prolonged high-temperature heating. They must support the weight of the heated workpieces and avoid significant deformation or even collapse. High-temperature strength depends on the material and structure of the fixtures. However, if the structure is too strong, it will be heavy and absorb more heat, increasing energy consumption per unit of workpiece, prolonging heating time, and raising production costs. Metal trays, such as those used in vacuum carburizing and quenching furnaces, are heavy and have a high heat capacity. This increases the quenching fluid temperature, reducing its cooling capacity. Repeated heating, carburizing, and quenching of the trays also causes phase changes within the trays, inducing structural stress. This, combined with thermal fatigue, can lead to cracks in the trays, significantly reducing their service life. Furthermore, the heavy weight and high heat capacity of metal trays require additional energy. Vacuum furnace fixtures made of alloy materials at high temperatures (1200°C) have a short service life. Practice has shown that the difference between the surface and core temperatures of the workpiece (heating and cooling unevenness) during the heating and cooling processes is the primary factor causing heat treatment fixture deformation. (Vacuum furnaces have the ability to control heating and cooling rates.) Different process methods can adapt heat treatment fixtures to different operating conditions and performance requirements.

[0003] The manufacture of heat treatment tooling involves several manufacturing and processing technologies and equipment. It is used to perform workpiece loading, furnace loading and unloading, quenching, and workpiece transfer operations. It is also a crucial tool for ensuring smooth production, quality, and safe operation during heat treatment. Heat treatment tooling is generally divided into two types: general-purpose tooling and specialized tooling. General-purpose tooling is designed and manufactured primarily to accommodate furnace types and is suitable for heat treatment of large quantities of common workpieces. Its functions include loading and unloading workpieces, clamping them during heating and cooling, minimizing workpiece deformation during heat treatment, and performing certain auxiliary heat treatment tasks. Specialized tooling is designed and manufactured primarily based on the workpiece's specific needs and furnace type, meeting the specific loading requirements of the workpiece. Due to the diverse shapes and sizes of heat treatment workpieces and the variety of heat treatment furnace types, the tooling used for heat treatment also varies. For workpieces with complex shapes and strict dimensional requirements, specialized tooling is required to ensure specific dimensional accuracy. For some large and heavy workpieces, to facilitate loading and unloading from the furnace, and to maintain vertical heating and quenching during heat treatment, specialized tooling is required based on the furnace type. General-purpose and specialized tooling have very different functions, so they cannot be used interchangeably.

[0004] The heat energy required to heat fixtures is generally 18% to 29% of the weight of the heat source. Therefore, reducing fixture weight is crucial for improving heating efficiency. One way to reduce weight is to improve fixture structure. Heat treatment fixtures play a crucial role in vacuum heat treatment. Optimizing fixture design and selecting the right fixtures for different product structures, heat treatment materials, and process requirements is crucial for improving heat treatment quality and production efficiency.

[0005] Vacuum heat treatment furnaces are advanced heat treatment equipment that have seen significant development in recent years. Currently, heat treatment methods using vacuum furnaces are generally performed by heat treatment workshops. Vacuum heat treatment is a novel heat treatment technology that combines vacuum and heat treatment techniques. The vacuum environment used in vacuum heat treatment refers to an atmosphere below one atmosphere, including low vacuum, medium vacuum, high vacuum, and ultra-high vacuum. Vacuum heat treatment involves performing the heat treatment process entirely or partially under vacuum. Vacuum heat treatment can perform nearly all heat treatment processes common to conventional heat treatment. Vacuum can refer to any gaseous space with a pressure less than one atmosphere (negative pressure). When heat treatment of metals is performed in a vacuum, it is called vacuum heat treatment. Vacuum heat treatment can perform nearly all heat treatment processes, such as quenching, annealing, tempering, carburizing, chromizing, nitriding, and precipitation hardening. Quenching processes can include gas quenching, oil quenching, nitrate quenching, water quenching, and degassing. Because vacuum heat treatment involves heating and cooling metal workpieces, it requires dozens of steps. These operations take place within a vacuum heat treatment furnace, inaccessible to operators. Therefore, a high level of automation is required for vacuum heat treatment furnaces. Furthermore, some operations, such as the quenching of metal workpieces after heating and holding, require six or seven steps and must be completed within 15 seconds. Completing so many steps in such a short period of time can easily lead to operator anxiety and errors. During the heating process, the workpiece and the materials in the furnace release gas, causing the vacuum level to drop. Vacuum heat treatment processes for stainless steel, titanium alloys, and high-temperature alloys present a relatively high level of difficulty. Surface discoloration is a common problem during vacuum heat treatment. Achieving a bright, non-discoloring finish is a common goal for vacuum furnace developers, manufacturers, and users, and a significant concern for frontline technicians. Different colors are related to the temperature at which the oxide film forms and the thickness of the oxide film. Quenching in oil at 1200°C can also cause surface carburization and melting, while excessive vacuum levels can cause element volatilization and adhesion, all of which can impair surface gloss. It is easier to obtain a bright surface in a vacuum furnace, because it is not easy to obtain a protective atmosphere with a dew point of -74°C and the cost is very high.

[0006] Currently, ultra-high-strength steel is used for critical heat-treated workpieces such as aviation shafts, thin-walled cylinders, hollow shafts, special-shaped structures, long-axis screws, and tubes. This material is heated to a predetermined temperature in a vacuum quenching furnace, held there for a period of time, and then quenched to achieve a martensitic structure. While this method achieves high strength and hardness, it also increases deformation and is prone to cracking during straightening. Summary of the Invention

[0007] The purpose of the present invention is to overcome the shortcomings of the existing technology, adapt to actual needs, and provide a method for heat treatment of different heat-treated workpieces in a vacuum furnace, which has a simple structure, strong operability, easy size adjustment, good durability, small distortion of parts after vacuum heat treatment, high quality, and can improve the processing efficiency of heat-treated workpieces in subsequent processing, as well as a variable combined heat treatment tooling for loading shaft heat-treated parts to meet the requirements of heat treatment process capabilities.

[0008] The solution adopted by the present invention to solve its technical problem is: a heat treatment method for completing different heat treatment workpieces in a vacuum furnace, which has the following technical features: first, a variable combined heat treatment tool for loading shaft heat treatment parts in a vacuum furnace is prepared, and two tool support body units 1 are symmetrically distributed in the same direction and fixed at the longitudinal end of the heat treatment material plate 11 in the heat treatment tool, characterized in that: a through groove and a right-angled trapezoidal wedge-shaped moving block 4 assembled in the through groove are formed on the ╬-shaped seat 12 of each tool support body unit 1, and each wedge-shaped moving block 4 is formed on the inclined surface There are guide rail grooves parallel to the inclined surface and a dividing block connected to the same body, and the dividing block is fixed to the above-mentioned ╬-shaped seat body 12 by bolts 7. The trapezoidal slider 3 with a guide hole on the back end passes through the guide rail groove on the inclined surface of the wedge-shaped moving block 4, which is symmetrical to the spacing groove formed by the two dividing blocks. The guide rod 2 with an internal bevel gear on the shaft end is positioned on the inclined surface of the middle isosceles top block 8 through the guide hole by the core shaft 9 embedded in the center of the internal bevel gear. A pair of symmetrically separated bevel gears are made in the transmission shaft 6 and mesh with the internal bevel gear on the shaft end of the guide rod 2 to form a two-axis movement of the guide rod. The movable two-wing trapezoidal slider 3 supports the V-cross angle structure of the heat treatment workpiece 10, and a pair of separated bevel gears of the transmission shaft 6 are embedded in the grooves corresponding to the ╬-shaped seat body 12. The transmission shaft 6 is fixed by two bearing bushes 5 at the bottom end of the bearing groove of the tool support unit 1, thereby forming a heat treatment method for completing different heat treatment workpieces in a vacuum furnace; the pair of separated bevel gears of the transmission shaft 6 drives the bevel gear inside the guide rod 2 to rotate, driving the trapezoidal slider 3 to move obliquely along the specified direction of the guide groove of the wedge-shaped moving block 4, and realizes linear motion between the trapezoidal slider 3 and the worm gear. The shaped slider 3 moves to both sides along the designated guide rail slope, thereby realizing the adjustment of the support position of the heat treatment workpiece 10; referring to the data of various types of organizational transformation under normal pressure, inert gas is filled, and in addition to high-pressure gas quenching, vacuum is first evacuated, and then high-pressure inert gas is filled in a closed vacuum furnace and convection heating is performed. The vacuum degree required for non-oxidizing heating is utilized, and heating is performed in a vacuum medium at 10~1Pa to the required temperature, and then cooling is performed at different cooling rates in different media to meet the ability of different heat treatment workpiece products to complete heat treatment in the same vacuum heat treatment furnace.

[0009] Compared with the prior art, the present invention has the following beneficial effects:

[0010] The present invention adopts a tooling that can adjust the support surface position according to the size of the heat-treated workpiece and prevent the heat-treated workpiece from being deformed during heat treatment. It has two tooling support body units 1 for fixed installation with the longitudinal end of the heat-treated material plate (11). The two-wing trapezoidal sliders 3 that are symmetrically distributed and fixed on the heat-treated material plate to form a V-intersection angle structure of the heat-treated workpiece 10 and move along two axes of the guide rod. The guide rod 2 moves the trapezoidal slider 3 along the specified direction to bear the weight of the heated workpiece. The two-wing trapezoidal sliders formed complete the heat treatment method of different heat-treated workpieces in the vacuum furnace. The loaded workpiece controls the deformation amount of the shaft-type heat-treated workpiece in the actual heat treatment, reduces a lot of correction time after heat treatment, and heats for a long time at high temperature, which has little bending distortion on the shaft-type workpiece. In addition, the structure is simple, and no hanging basket, mesh basket, or hanger is needed. The workpiece is conveniently clamped in and out of the furnace and during heating and cooling, which can reduce the deformation of the workpiece during heat treatment and will not cause serious deformation or disintegration.

[0011] The present invention is connected to the heat treatment material plate through the ╬-shaped base body 12. The contact surface of the ╬-shaped base body 12 with the heat treatment material plate is designed with a mounting slot and a positioning boss. This variable modular tooling provided for vacuum heat treatment of shaft-type heat treatment workpieces can realize the support and fixation of the tooling during the heat treatment process. It has a simple structure, good durability, and strong operability. The size can be adjusted quickly and conveniently by using the through groove and the right-angled trapezoidal wedge-shaped moving block 4 assembled in the through groove on the ╬-shaped base body 12 of each tooling support body unit 1. The method of mounting the heat treatment workpiece between the trapezoidal sliders 3 that match each other between the two tooling support body unit bodies is not only flexible and stable, but also has low heat energy loss, reduces the heat loss of the material tray, and reduces costs. In addition, the guide rail grooves on the inclined surfaces of the wedge-shaped moving block 4 and the sliding of the guide rails increase the loading angle. The workpiece being processed is heated slowly in the furnace, the internal temperature difference is small, the thermal stress is small, and there is a degassing effect, so the deformation is small, the product qualification rate is high, the cost can be reduced, and the mechanical properties and service life of the workpiece are improved.

[0012] The present invention adopts a guide rod with an internal bevel gear at the end of the shaft, which is positioned on the isosceles inclined surface of the top block 8 through the guide hole by a core shaft embedded in the center of the internal bevel gear. A pair of symmetrically separated bevel gears facing each other are made in the transmission shaft 6, which mesh with the internal bevel gear on the end of the guide rod 2, forming a V-cross angle structure in which the two-axis movement of the guide rod and the two-wing trapezoidal slider 3 support the heat treatment workpiece. The guide rod is positioned on the inclined surface of the isosceles middle block by the core shaft, and is connected to the gear structure on the guide rod through the helical teeth on the shaft, driving the guide rod to rotate, and realizing linear motion between the slider and the screw transmission method, so that the slider moves on both sides along the inclined surface of the fixed guide rail, realizing the adjustment of the support position of the heat treatment workpiece with good stability and repeatability, thereby improving the heat treatment efficiency of the heat treatment workpiece.

[0013] The present invention uses a trapezoidal slider with a guide hole formed on the back end, which is symmetrically aligned with the spacing groove formed by the two partition blocks through the guide rail groove on the inclined surface of the wedge-shaped moving block. By replacing different types of sliders, different types of heat treatment workpieces 10 can be heat treated. By replacing the same type of sliders with different sizes, the same type of heat treatment workpieces 10 with different sizes can be heat treated. For certain large and bulky workpieces, there is no need to design and manufacture them according to the furnace type, nor is there a need to design complex special tooling according to the furnace type. Not only is the workpiece highly versatile, but it is also convenient for entering and exiting the furnace.

[0014] The present invention adopts helical gear drive as the contact driving mode of the rotating shaft and the guide rod, and screw drive as the transmission mode of the guide rod and the slider, which has stable transmission, large load-bearing capacity and high efficiency; it is flexible in operation of the vacuum heat treatment process of key shaft heat treatment workpieces such as current aviation shafts, thin-walled cylinders, hollow shafts and special-shaped structures, long shaft screws, pipes, etc., provides a method for controlling the deformation of shaft heat treatment workpieces in actual heat treatment, and reduces a lot of correction time after heat treatment.

[0015] The heat treatment tooling of the present invention utilizes a heat treatment technology that combines vacuum heat treatment furnace processing technology with heat treatment technology, achieving zero oxidation, zero decarburization, and zero carburization, removing phosphorus shavings from the workpiece surface, and performing degreasing and degassing. Controlled atmosphere heat treatment under vacuum conditions reduces operating and maintenance costs. Furthermore, in addition to high-pressure gas quenching, convection heating after first evacuating the vacuum and then filling with high-pressure inert gas can more than double the speed of traditional vacuum radiation heating, significantly improving heating efficiency. Workpieces are easy to clean after quenching, and are non-corrosive and non-irritating to equipment. Vacuum heat treatment reduces distortion in heat-treated workpieces, significantly improving their service life compared to conventional heat treatment. Parts undergoing vacuum heat treatment exhibit minimal distortion and high quality, while the process itself is flexible and pollution-free. Furthermore, the tooling has also been applied in the heat treatment of general engineering steel, particularly tools, molds, and precision couplings, which have significantly improved service life compared to conventional heat treatment. For example, after vacuum heat treatment, the lifespan of some molds is 40-400% longer than that of those treated with salt baths, and the lifespan of many tools can be increased by approximately 3-4 times. Compared to conventional heat treatment, vacuum heat-treated workpieces exhibit greater oxidation and corrosion resistance, and possess a denser microstructure. The surface finish and cleanliness of heat-treated workpieces are significantly improved. Heat treatment tooling can operate at higher temperatures in vacuum heating furnaces, extending its lifespan by 40-400% compared to salt bath treatment. This improves the efficiency of subsequent processing of heat-treated workpieces. Practice has shown that the correct heat treatment process can produce superior microstructure, and superior microstructure morphology guarantees excellent mechanical properties. Appropriate process methods can effectively control deformation and cracking of heat treatment tooling.

[0016] The variable modular tooling provided by the present invention for vacuum heat treatment of shaft-type heat treatment workpieces has the characteristics of simple structure, good durability, strong operability, and easy size adjustment. It controls the deformation of shafts, thin-walled cylinders and special-shaped structure heat treatment workpieces during actual heat treatment, reduces a lot of correction time after heat treatment, and improves the processing efficiency of heat treatment workpieces in subsequent processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the working state of loading shaft heat treatment parts in a vacuum furnace according to the present invention;

[0018] Figure 2 yes Figure 1 3D schematic diagram of the tooling support unit;

[0019] Figure 3 yes Figure 2 Axial cross-sectional view of

[0020] Figure 4 It is a partially enlarged schematic diagram of the removed section of Figure 1-1;

[0021] Figure 5 It is a decomposition diagram of the graph;

[0022] Figure 6 yes Figure 2 A schematic diagram of the ╬-shaped seat body 12;

[0023] Figure 7 yes Figure 2 Schematic diagram of the wedge-shaped moving block;

[0024] In the figure: 1 tooling support unit, 2 guide rod, 3 trapezoidal slider, 4 wedge-shaped moving block, 5 bearing bush, 6 transmission shaft, 7 bolt, 8 top block, 9 core shaft, 10 heat-treated workpiece, 11 heat-treated material plate, 12 ╬-shaped seat. DETAILED DESCRIPTION

[0025] See Figure 1-Figure 7According to the present invention, a variable modular heat treatment fixture for loading shaft heat treatment parts in a vacuum furnace is first prepared, in which two fixture support body units 1 are symmetrically distributed in the same direction and fixed at the longitudinal ends of the heat treatment material plate 11. The characteristics are as follows: a through groove and a right-angled trapezoidal wedge-shaped moving block 4 assembled in the through groove are formed on the ╬-shaped seat body 12 of each fixture support body unit 1, and a guide rail groove parallel to the inclined surface and a partition block connected to the body are formed on the inclined surface of each wedge-shaped moving block 4, and the partition block is fixed to the On the above-mentioned ╬-shaped seat body 12, a trapezoidal slider 3 with a guide hole on the back end is symmetrically connected to the spacing groove formed by the two partition blocks through the guide rail groove on the inclined surface of the wedge-shaped moving block 4. The guide rod 2 with an internal bevel gear on the shaft end is positioned on the inclined surface of the middle isosceles top block 8 through the guide hole by the core shaft 9 embedded in the center of the internal bevel gear. A pair of symmetrically separated bevel gears are made in the transmission shaft 6 and mesh with the internal bevel gear on the shaft end of the guide rod 2, forming a V-cross angle between the two wings of the guide rod 3 supporting the heat treatment workpiece 10. Structure, a pair of separated bevel gears of the transmission shaft 6 are embedded in the grooves corresponding to the ╬-shaped seat body 12, and the transmission shaft 6 is fixed by two bearing bushes 5 at the bottom end of the bearing groove of the tooling support body unit 1, thereby forming a heat treatment method for completing different heat treatment workpieces in a vacuum furnace; rotating the transmission shaft 6, a pair of separated bevel gears drive the bevel gear inside the guide rod 2 to rotate, driving the trapezoidal slider 3 to move obliquely along the specified direction of the guide groove of the wedge-shaped moving block 4, and realizing linear motion between the worm gear and the trapezoidal slider 3, so that the trapezoidal slider 3 moves on both sides along the specified guide rail inclined surface, thereby realizing the adjustment of the support position of the heat treatment workpiece 10; referring to the data of various types of organizational transformation under normal pressure, inert gas is filled, and except for high-pressure gas quenching, vacuum is first drawn, and then high-pressure inert gas is filled in the closed vacuum furnace and convection heating is performed, and the vacuum degree required for non-oxidizing heating is utilized to heat the vacuum medium at 10~1Pa to the required temperature, and then cool at different cooling rates in different media to meet the ability of different heat treatment workpiece products to complete heat treatment in the same vacuum heat treatment furnace.

[0026] In an optional embodiment, the heat-treated material plate (11) below the V-shaped seat 12 is made of heat-resistant alloy steel, graphite material or carbon / carbon (C / C) composite material made by chemical vapor infiltration process, which is woven into a grid-like honeycomb plate. The carbon / carbon C / C composite material consists of two main parts, carbon fibers and a carbon matrix or binder interwoven together. The carbon fibers are composed of extremely fine filaments of carbon atoms, with a diameter of usually only 0.005 to 0.01 mm. They have excellent mechanical strength, hardness and thermal conductivity. The carbon matrix in which they are enclosed can uniformly reduce weight and withstand chemical effects. The carbon / carbon composite material has a small heat capacity, high high-temperature strength, and negligible thermal deformation. The net weight / tare weight ratio is very suitable for the production of the material rack, which can accelerate the heating and cooling speed, increase the capacity of the load-bearing components, and reduce the deformation of the components. The carbon / carbon composite material also has excellent thermal fatigue resistance, and the crack propagation is greatly reduced. Honeycomb panels woven with carbon ropes create a grid-like structure, boasting lightweight, excellent air permeability, resistance to ablation, corrosion, and wear, high-temperature strength, strong load-bearing capacity, no deformation, and guaranteed dimensional stability. C / C honeycomb grid panels are lightweight, have minimal heat storage, and minimal impact on the quenching fluid temperature, ensuring the quenching fluid's cooling capacity. They are also extremely convenient to operate, significantly reducing labor intensity. Their low heat capacity allows for rapid heating and cooling, and they maintain consistent lag with furnace temperature changes, significantly shortening process cycles and saving energy. Carbon / carbon materials undergo no structural transformation and are immune to phase change stress during rapid cooling and heating, extending the life of the feed trays. This reduces both feed rack weight and energy consumption. The time it takes for the charge to reach the specified temperature (857°C) is 35 minutes shorter than using alloy feed racks, and the cooling rate is 10 minutes faster (to 65°C). The feed trays remain unchanged after repeated use at temperatures up to 1200°C.

[0027] Graphite material has the characteristics of high temperature resistance, oxidation resistance, corrosion resistance, and high high temperature strength. Therefore, graphite material can be used to manufacture heat treatment material plates (11). For example, when a vacuum furnace with a working area size of 1200mm×1200mm×1800mm is used to perform solid solution and annealing treatment at high temperature, the workpiece during vacuum heat treatment not only increases the output but also obtains an ideal service life.

[0028] In the preferred embodiment described below, the tool support unit 1 is made of at least one of chromium-manganese-nitrogen austenitic heat-resistant steel, heat-resistant alloy or austenitic stainless steel that is resistant to oxidation, sulfur corrosion and carburization, wherein the carburization-resistant chromium-manganese-nitrogen austenitic heat-resistant steel component material is Ni3A l The material composition is to add Cr, Zr, Mo, and B with a mass fraction of 35% to 88% Ni, 8% to 11% Al, and the amount of Cr added can be 20% to 26% Cr. lThe life of the components is more than double that of heat-resistant steel. This ceramic material has excellent thermal strength, creep resistance, and carburizing resistance. The mass fractions of the heat-resistant alloys are 37% Ni-18% Cr (maximum operating temperature 1000°C) and 80% Ni-20% Cr (maximum operating temperature 1280°C). The fixtures can obtain ideal structure and high-temperature strength to reduce heat loss and increase furnace loading. These two alloys have obvious advantages over stainless steel. They have high thermal strength, good high-temperature creep resistance, good thermal fatigue performance, and long service life. They can also withstand embrittlement and other factors caused by different heat treatment atmospheres (such as oxidation, carburizing, nitriding, etc.). Ni3A l The manufactured components can also increase heat treatment production efficiency by 10% due to the extended service life and reduced weight.

[0029] In an optional embodiment, a screw thread is formed on the rod body of the V-shaped symmetrical guide rod 2 to cause the guide rod 2 to rotate. The guide rod 2 passes through the guide hole of the V-shaped symmetrical trapezoidal slider 3, and is driven by a screw transmission method with a pair of separated bevel gears on the terminal engaging the rotating shaft 6.

[0030] The bottom plate of the ╬-shaped seat body 12 is connected to the heat treatment material plate 11, and the contact surface between the bottom plate and the heat treatment material plate 11 is designed with mounting slots and positioning bosses that can support and fix the tooling during the heat treatment process. Tooling support unit (1)

[0031] The wedge-shaped moving block 4 with the guide groove is fixed to the seat plates on both sides of the ╬-shaped seat body 12 by bolts 7. The bearing bush 5 is fixed to the bottom end of the through groove through the bearing seat holes on both sides of the through groove of the tool support body unit 1. The transmission shaft (6) is supported by the bearing bush 5. The inner conical helical teeth of the pair of separating bevel gears on the shaft are meshed with the matching gear tooth surfaces on the two guide rods 2, driving the guide rods 2 to rotate, so that the slide-shaped slider (3) moves to both sides along the inclined surface of the guide groove. The inner conical gear at the end of the guide rod 2 is positioned on the isosceles inclined surface of the top block 8 in the middle of the separating bevel gear through the core shaft 9.

[0032] The guide rod 2 realizes linear motion with the trapezoidal slider 3 through screw transmission, and the trapezoidal slider 3 supporting the heat treatment workpiece 10 moves along a specified direction, thereby realizing adjustment of the support position of the heat treatment workpiece 10.

[0033] The middle isosceles top block 8 is fixed to the upper end of the through slot through the grooves on both sides of the middle position of the tooling support unit 1. The two isosceles inclined surfaces are used to support the gear end face of the guide rod 2 and ensure that the guide rod 2 and the trapezoidal slider 3 are evenly distributed on both sides of the top block 2 along a certain angle.

[0034] The bevel gear of the rotating shaft 6 and the conical gear of the guide rod 2 are engaged and contacted in a helical gear drive mode, which drives the guide rod 2 to rotate and drives the trapezoidal slider 3 to move obliquely along the specified direction of the guide rail groove of the wedge-shaped moving block 4.

[0035] By replacing different types of trapezoidal sliders 3, heat treatment work can be achieved for heat-treated workpieces 10 of the same type but different sizes.

[0036] In an optional embodiment, during vacuum nitriding, after venting the vacuum furnace to a relatively high vacuum of 0.133 Pa, the workpiece is heated to 530-560°C while ammonia or a composite gas is introduced simultaneously. The amount of each gas introduced is precisely controlled, and the furnace pressure is maintained at 0.667 Pa. The low pressure accelerates gas exchange on the workpiece surface. The active nitrogen (or N, C) element comes from chemical reactions and ammonia. After 3-5 hours of holding, the workpiece is rapidly cooled using inert gas within the furnace. This treatment can produce a hardened layer with a depth of 20-80 μm and a hardness of 600-1500 HV for different materials. X-ray diffraction analysis confirms that after vacuum nitriding, the compound layer in the nitrided layer is a single-phase ε structure, free of other brittle elements, with high hardness and excellent toughness. Using a heating rate of 10-1 Pa, equivalent to an inert gas purity of more than 1 PPM, generally prevents oxidation of ferrous metals.

[0037] During vacuum infiltration, the vacuum furnace is vented to a relatively high vacuum of 0.133 Pa (1×10-3 Torr). The workpiece is then heated to 530-560°C. A variety of composite gases, primarily ammonia, containing active substances are introduced simultaneously. The amount of each gas introduced is precisely controlled, and the furnace pressure is controlled at 0.667 Pa (5 Torr). After holding the temperature for 3-5 hours, the workpiece is rapidly cooled using inert gas in the furnace. This treatment can produce a hardened layer with a depth of 20-80 μm and a hardness of 600-1500 HV for different materials.

[0038] In an optional embodiment, when an inert gas is filled, such as a nitrogen-hydrogen mixed gas (50% N2 + 50% H2) at 133 Pa, the effect is better than a vacuum of 10-2 to 10-3 Pa. At this time, an oxygen partial pressure of 66.5 Pa is safe.

[0039] The above description is only a preferred embodiment of the present invention, but does not limit the present invention to the scope of the described embodiments. For engineers and technicians in this field, various changes and variations are possible. Any modifications, equivalent replacements, and improvements made using the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for heat treating workpieces of different heat treatments in a vacuum furnace, having the following technical features: first, a variable modular heat treatment tool for loading shaft heat treatment parts in a vacuum furnace is prepared, wherein two tool support body units (1) are symmetrically distributed in the same direction and fixed to the longitudinal ends of the heat treatment material plate (11), and each tool support body unit (1) has a through groove and a right-angled trapezoidal wedge-shaped moving block (4) assembled in the through groove on a ╬-shaped seat (12), and each wedge-shaped moving block (4) is provided with a guide rail groove parallel to the inclined surface and a partition connected to the same body on the inclined surface. The spacer block is fixed on the above-mentioned ╬-shaped seat body (12) by bolts (7). The trapezoidal slider (3) with a guide hole on the back end is symmetrical to the spacing groove formed by the two spacer blocks through the guide rail groove on the inclined surface of the wedge-shaped moving block (4). The guide rod (2) with an internal bevel gear on the shaft end is positioned on the inclined surface of the middle isosceles top block (8) through the guide hole by the core shaft (9) embedded in the center of the internal bevel gear. A pair of symmetrically separated bevel gears are formed in the transmission shaft (6) and mesh with the internal bevel gear on the shaft end of the guide rod (2), forming a two-axis motion two-wing trapezoidal slider (3) of the guide rod The V-shaped cross angle structure supports the heat treatment workpiece (10), and a pair of separated bevel gears of the transmission shaft (6) are embedded in the grooves corresponding to the ╬-shaped seat body (12). The transmission shaft (6) is fixed by two bearing bushes (5) at the bottom end of the bearing groove of the tool support body unit (1); the pair of separated bevel gears of the rotation transmission shaft (6) drives the inner bevel gear of the guide rod (2) to rotate, and the rotation of the screw structure on the guide rod (2) drives the trapezoidal slider (3) with the inner screw structure to move obliquely along the specified direction of the guide groove of the wedge-shaped moving block (4), and realizes linear rotation between the screw transmission mode and the trapezoidal slider (3). Movement causes the trapezoidal slider (3) to move to both sides along the designated guide rail slope, thereby realizing the adjustment of the support position of the heat-treated workpiece (10); referring to the data of various types of organizational transformations under normal pressure, filling with inert gas, except for high-pressure gas quenching, first evacuating, and then filling the closed vacuum furnace with high-pressure inert gas and performing convection heating, utilizing the vacuum required for non-oxidizing heating, heating to the required temperature in a vacuum medium at 10 to 1 Pa, and then cooling at different cooling rates in different media, so as to meet the ability of different heat-treated workpiece products to complete heat treatment in the same vacuum heat treatment furnace.

2. The heat treatment method for completing different heat treatment workpieces in a vacuum furnace according to claim 1, characterized in that: During vacuum nitriding, after the vacuum furnace is exhausted to a relatively high vacuum degree of 0.133Pa, the workpiece is raised to 530-560℃, and ammonia or compound gas is introduced at the same time. The amount of each gas introduced is precisely controlled and the furnace pressure is controlled at 0.667Pa. The low-pressure state can accelerate the gas exchange on the surface of the workpiece. The active N element (or N, C) comes from chemical reactions and ammonia. After keeping warm for 3-5 hours, it is quickly cooled with inert gas in the furnace.

3. The heat treatment method for completing different heat treatment workpieces in a vacuum furnace according to claim 1, characterized in that: The tool support unit (1) is made of at least one of chromium-manganese-nitrogen austenitic heat-resistant steel, heat-resistant alloy or austenitic stainless steel with oxidation resistance, sulfur corrosion resistance and carburization resistance, wherein the carburization-resistant chromium-manganese-nitrogen austenitic heat-resistant steel component material is Ni3A l The material composition is Cr, Zr, Mo, and B, with a mass fraction of 35% to 88% Ni, 8% to 11% Al, and a Cr addition amount of 20% to 26% Cr.

4. The heat treatment method for completing different heat treatment workpieces in a vacuum furnace according to claim 1, characterized in that: A bevel gear structure for causing the guide rod (2) to rotate is formed on the rod body of the V-shaped symmetrical guide rod (2). The guide rod (2) passes through a guide hole of a V-shaped symmetrical trapezoidal slider (3) and is driven by a worm drive method in which a symmetrical bevel gear on a terminal engages a transmission shaft (6) with a pair of separated bevel gears.

5. The heat treatment method for completing different heat treatment workpieces in a vacuum furnace according to claim 1, characterized in that: The bottom plate of the ╬-shaped seat body (12) is connected to the heat treatment material plate (11), and the contact surface between the bottom plate and the heat treatment material plate (11) is designed with a mounting slot and a positioning boss that can realize the support and fixing function of the tooling during the heat treatment process.

6. The heat treatment method for completing different heat treatment workpieces in a vacuum furnace according to claim 1, characterized in that: The wedge-shaped moving block (4) with a guide rail groove and the two-wing screw hole positioning rectangular seat blocks are fixed to the seat plates on both sides of the ╬-shaped seat body (12) through bolts (7).

7. The heat treatment method for completing different heat treatment workpieces in a vacuum furnace according to claim 1, characterized in that: The bearing bush (5) is fixed at the bottom end of the through groove through the bearing seat holes on both sides of the through groove of the tool support body unit (1); the transmission shaft (6) is supported by the bearing bush (5), and the inner conical helical teeth of a pair of separating bevel gears on the shaft are meshed with the matching gear tooth surfaces on the two guide rods (2), driving the guide rods (2) to rotate, so that the trapezoidal slider (3) moves to both sides along the inclined surface of the guide groove; the inner conical gear at the end of the guide rod (2) is positioned on the isosceles inclined surface of the top block (8) in the middle of the separating bevel gear through the core shaft (9).

8. The heat treatment method for completing different heat treatment workpieces in a vacuum furnace according to claim 1, characterized in that: The guide rod (2) realizes linear motion with the trapezoidal slider (3) through screw transmission, and the trapezoidal slider (3) supporting the heat-treated workpiece (10) moves along a specified direction, thereby realizing adjustment of the support position of the heat-treated workpiece (10).

9. The heat treatment method for completing different heat treatment workpieces in a vacuum furnace according to claim 1, characterized in that: The middle isosceles top block (8) is fixed to the upper end of the through slot through grooves on both sides of the middle position of the tool support body unit (1). The two isosceles inclined surfaces are used to support the gear end face of the guide rod (2) and ensure that the guide rod (2) and the trapezoidal slider (3) are evenly distributed on both sides of the top block (8) along a certain angle.

10. The heat treatment method for completing different heat treatment workpieces in a vacuum furnace according to claim 1, characterized in that: The bevel gear of the transmission shaft (6) and the conical gear of the guide rod (2) are meshed and contacted to drive the guide rod (2) in a helical gear drive mode, which drives the guide rod (2) to rotate and drives the trapezoidal slider (3) to move obliquely along the specified direction of the guide rail groove of the wedge-shaped moving block (4); by replacing different types of trapezoidal sliders (3), heat treatment work can be achieved for heat-treated workpieces (10) of the same type but different sizes.

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