Gear pressure quenching device

Abstract

The utility model relates to a gear pressure quenching device which comprises a horizontal workbench, a gear tray is arranged on the workbench, and the gear tray is connected with a driving mechanism for driving the gear tray to do reciprocating rectilinear motion; a quenching blind hole is formed in the upper surface of the gear tray, the diameter of the quenching blind hole is larger than the addendum circle diameter of the gear, and the depth of the quenching blind hole is larger than the thickness of the gear; the quenching blind hole is connected with a quenching liquid supply mechanism and a quenching liquid discharge mechanism; a pressure mechanism is arranged above the gear tray and connected with a pressure head, and the diameter of the pressure head is matched with that of the quenching blind hole. Axial pressure is applied to the carburized gear, so that the gear generates tiny plastic deformation, the stability of austenite is reduced, and residual austenite can be quickly and fully converted into martensite in the quenching process.

Description

Technical Field

[0001] This utility model belongs to the field of quenching equipment, and in particular a gear pressure quenching device. Background Technology

[0002] Currently, the heat treatment process for automotive transmission gears includes steps such as carburizing, quenching, and low-temperature tempering. While carburizing can improve the surface hardness of the gears, it often results in a high residual austenite content (>10%), leading to a decrease in fatigue life at the gear meshing points. Existing heat treatment processes typically employ methods such as reducing the carburizing thickness and carbon potential, adjusting the quenching temperature, extending the quenching time, and performing multiple tempering processes to reduce the residual austenite content, but the effects are generally poor. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide a gear pressure quenching device that can more effectively reduce the content of residual austenite.

[0004] To solve the above problems, the technical solution adopted by this utility model is: a gear pressure quenching device, including a horizontal worktable, a gear tray is provided on the worktable, and the gear tray is connected to a drive mechanism that drives the gear tray to reciprocate linear motion.

[0005] The upper surface of the gear tray is provided with a quenching blind hole. The diameter of the quenching blind hole is larger than the tooth tip circle diameter of the gear, and the depth of the quenching blind hole is larger than the thickness of the gear. The quenching blind hole is connected to a quenching fluid supply mechanism and a quenching fluid discharge mechanism.

[0006] A pressure mechanism is provided above the gear tray, and the pressure mechanism is connected to a pressure head. The diameter of the pressure head is adapted to the diameter of the quenched blind hole.

[0007] Furthermore, the quenching fluid supply mechanism includes an inlet hose disposed on the side wall of the quenching blind hole, and the inlet hose is connected to the quenching fluid tank via a pump.

[0008] Furthermore, the quenching fluid discharge mechanism includes a drain hole, which is connected to a drain hose via an overflow valve, and the drain hose is connected to the quenching fluid tank.

[0009] Furthermore, the inlet hose and the outlet hole are located on the two side walls of the quenching blind hole, and the inlet hose is higher than the outlet hole.

[0010] Furthermore, the bottom wall of the quenching blind hole is provided with a plurality of guide blind holes, and a support column that slides within the guide blind hole is provided, and a spring is provided between the lower end of the support column and the bottom of the guide blind hole.

[0011] Furthermore, a sealing sleeve is provided on the outer wall of the pressure head.

[0012] Furthermore, the driving mechanism is a hydraulic cylinder.

[0013] The beneficial effects of this utility model are as follows: After the gear is carburized, it is cooled to slightly below the Ar1 temperature and then placed into a quenching blind hole. A pressure mechanism is then used to drive the pressure head downward into the quenching blind hole. The pressure head applies appropriate pressure to the gear, causing the gear to undergo a small axial compression deformation, with a deformation of 0.3% ≥ 0.1%. Then, a quenching liquid supply mechanism is used to transport the quenching liquid into the quenching blind hole, while a quenching liquid discharge mechanism is used to discharge the quenching liquid, thereby rapidly cooling the gear.

[0014] Before quenching, this invention applies axial pressure to the carburized gear, causing minute plastic deformation and austenite lattice slip, resulting in dislocations. The lattice distortion region around the dislocations stores elastic strain energy, reducing the energy barrier required for martensite nucleation. At the same time, the deformation of the material causes carbon atoms to dissolve from the austenite lattice, forming local carbon-depleted regions and reducing the stability of austenite. During the quenching process, the remaining austenite can be quickly and fully converted into martensite.

[0015] After heat treatment of automotive gearbox gears using the heat treatment process of this invention, XRD (X-ray diffraction analysis) was performed on the gears, and the residual austenite content in the carburized layer was less than 5%, which is far lower than that of conventional heat treatment processes. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the front sectional view of this utility model;

[0017] Figure 2 yes Figure 1 Schematic diagram of the AA section;

[0018] Reference numerals: 1—Workbench; 2—Gear tray; 3—Drive mechanism; 4—Quenching blind hole; 5—Drain hole; 6—Overflow valve; 7—Drain hose; 8—Inlet hose; 9—Pump; 10—Quenching liquid tank; 11—Pressure mechanism; 12—Pressure head; 14—Support column; 15—Spring; 16—Sealing sleeve Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] The gear pressure quenching device of this utility model, such as Figure 1 and Figure 2As shown, the system includes a horizontal worktable 1, which is horizontally positioned with a set of support legs at the bottom to maintain a suitable height. A gear tray 2 is mounted on the worktable 1, and the gear tray 2 is connected to a drive mechanism 3 that drives its reciprocating linear motion. The gear tray 2 slides within the worktable 1, and the drive mechanism 3 can move the gear tray 2 to the loading position, quenching position, and unloading position. The drive mechanism 3 can be a conventional mechanism such as a hydraulic cylinder or a motor-driven screw and nut mechanism.

[0021] The upper surface of the gear tray 2 is provided with a hardening blind hole 4. The diameter of the hardening blind hole 4 is larger than the tooth tip circle diameter of the gear, and the depth of the hardening blind hole 4 is larger than the thickness of the gear. After the gear is placed into the hardening blind hole 4, there is a certain gap between the side wall of the gear and the inner wall of the hardening blind hole 4, and the gear is completely located in the hardening blind hole 4.

[0022] The quenching blind hole 4 is connected to a quenching fluid supply mechanism and a quenching fluid discharge mechanism. The quenching fluid supply mechanism is used to deliver quenching fluid into the quenching blind hole 4, while the quenching fluid discharge mechanism is used to discharge the quenching fluid from the quenching blind hole 4, so as to realize the rapid flow of quenching fluid and ensure the cooling speed of the gear.

[0023] Specifically, the quenching fluid supply mechanism includes an inlet hose 8 installed on the side wall of the quenching blind hole 4. The inlet hose 8 is connected to a quenching fluid tank 10 via a pump 9. The quenching fluid tank 10 stores quenching fluid, which can be conventional quenching oil. The quenching fluid discharge mechanism includes a drain hole 5, which is connected to a drain hose 7 via an overflow valve 6. The drain hose 7 is connected to the quenching fluid tank 10. The quenching fluid can be discharged through the drain hole 5 and then returned to the quenching fluid tank 10 through the drain hose 7, achieving recycling. The inlet hose 8 and the drain hole 5 are located on the side walls of the quenching blind hole 4, respectively, ensuring that during quenching, the quenching fluid enters from one side of the gear and exits from the other side. Simultaneously, the inlet hose 8 is higher than the drain hole 5, increasing the coverage area of ​​the quenching fluid flow and allowing for uniform cooling of the gear.

[0024] A pressure mechanism 11 is provided above the gear tray 2, and a pressure head 12 is connected to the pressure mechanism 11. The diameter of the pressure head 12 is adapted to the diameter of the hardened blind hole 4. The pressure mechanism 11 can be a hydraulic mechanism, and an existing press can be used. The pressure head 12 can extend into the hardened blind hole 4 and apply downward pressure to the gear.

[0025] In use, the carburized gear is slowly cooled to slightly below Ar1 temperature (specifically, 650℃), then held at that temperature for 20 to 30 minutes. The gear is then quickly placed into the quenching blind hole 4. The drive mechanism 3 moves the gear tray 2 below the pressure mechanism 11, ensuring the quenching blind hole 4 is coaxial with the pressure head 12. The pressure mechanism 11 then moves the pressure head 12 downwards. After entering the quenching blind hole 4, the pressure head 12 applies a set pressure to the gear. After applying this pressure for 20 to 30 seconds, the pressure mechanism 11 moves the pressure head 12 upwards a certain distance, creating a gap between the pressure head 12 and the gear, with the lower end of the pressure head 12 remaining in the quenching blind hole 4. At this point, the pressure head 12 seals the opening of the quenching blind hole 4. Next, the pump 9 pressurizes the quenching liquid in the quenching liquid tank 10 and delivers it to the quenching blind hole 4. The quenching liquid quenches the gear and then discharges from the drain hole 5 and overflow valve 6, returning to the quenching liquid tank 10 via the drain hose 7. The overflow valve 6 ensures that the quenching fluid pressure inside the quenching blind hole 4 remains stable. Specifically, the pressure in the quenching blind hole 4 is maintained between 1.2 MPa and 1.6 MPa. Under higher pressure, the quenching fluid can fully contact the gear surface, achieving rapid quenching. At the same time, the flow rate of the quenching fluid is not less than 120 L / min to ensure rapid cooling of the gear.

[0026] The pressure applied by the pressure mechanism 11 can be determined by experimentation, that is, by conducting multiple experiments using the pressure quenching device of this utility model to determine the pressure range required for the axial compression of the gear to be 0.3% to 0.1% at a temperature of 650°C.

[0027] During quenching, the quenching fluid can flow through the gap between the side of the gear and the inner wall of the quenching blind hole 4, and the gap between the top surface of the gear and the pressure head 12. If the bottom surface of the gear contacts the bottom wall of the quenching blind hole 4, the quenching fluid cannot fully contact the bottom surface of the gear, resulting in uneven cooling of the gear. To solve this problem, this invention provides multiple guide blind holes on the bottom wall of the quenching blind hole 4. Each guide blind hole contains a support column 14 that slides within it. There can be three, four, or more guide blind holes, and each guide blind hole contains one support column 14. A spring 15 is installed between the lower end of the support column 14 and the bottom of the guide blind hole. After the gear is placed into the quenching blind hole 4, the support column 14 supports the gear, and there is a certain gap between the lower end face of the gear and the bottom wall of the guide blind hole. When the pressure head 12 applies pressure to the gear, it pushes the gear and support column 14 downwards, compressing the spring 15. This continues until the support column 14 is fully inserted into the guide blind hole, at which point the lower end face of the gear contacts the bottom wall of the guide blind hole. The pressure head 12 then applies a set pressure to the gear for 20 to 30 seconds. After slight deformation of the gear, the pressure head 12 moves upwards, and the spring 15 pushes the support column 14 back upwards. The support column 14 pushes the gear upwards a certain distance, causing the lower surface of the gear to detach from the bottom wall of the guide blind hole. During quenching, the quenching fluid can flow simultaneously over the side, upper, and lower surfaces of the gear, providing uniform cooling and ensuring quenching quality. The support column 14 and the guide blind hole have a good seal, preventing the quenching fluid from entering the guide blind hole.

[0028] Since the quenching fluid in the quenching blind hole 4 has a high pressure during quenching, in order to prevent the quenching fluid from leaking from the fitting gap between the pressure head 12 and the side wall of the quenching blind hole 4, a sealing sleeve 16 is provided on the outer wall of the pressure head 12. The sealing sleeve 16 can be a rubber sleeve.

[0029] The high temperature of the quenching fluid returning to the quenching fluid tank 10 may cause an overall temperature rise in the quenching fluid, affecting the cooling rate of the gears during continuous quenching. The quenching fluid tank 10 can be divided into multiple chambers: a supply chamber, a cooling chamber, and a recovery chamber, connected sequentially. The pump 9 is connected to the supply chamber, and the drain hose 7 is connected to the recovery chamber. A cooling mechanism, such as a heat exchanger, can be installed in the cooling chamber. For example, cold outside air can be introduced into the heat exchanger to exchange heat with the quenching fluid, thus lowering its temperature. A temperature sensor can be installed in the connecting channel between the supply chamber and the cooling chamber to detect the temperature of the quenching fluid, ensuring that the temperature of the coolant entering the supply chamber meets the requirements.

[0030] At temperatures slightly below the Ar1 temperature, such as 650℃, austenite is in a metastable state, carbon atoms remain supersaturated, and no pearlite or bainite transformation occurs, but the lattice distortion energy increases. When the gear is subjected to axial pressure and undergoes minor plastic deformation, austenite lattice slip occurs, generating dislocations. The lattice distortion region around the dislocations stores elastic strain energy, lowering the energy barrier required for martensite nucleation. Simultaneously, the deformation of the material causes carbon atoms to dissolve from the austenite lattice, locally forming carbon-depleted regions and reducing the stability of austenite. During subsequent quenching, the remaining austenite can be rapidly and fully converted into martensite.

[0031] Since the deformation of the gear is very small, it does not affect the dimensional accuracy of the gear. Furthermore, because quenching itself causes thermal deformation of the gear, in traditional processes, after heat treatment, the gear is usually ground to eliminate the thermal deformation caused by quenching, leaving a certain machining allowance before heat treatment. In this invention, the deformation caused by extrusion and the thermal deformation caused by quenching can be eliminated by the subsequent grinding process, ensuring the dimensional accuracy of the gear.

[0032] During quenching, the gear is rapidly cooled to the Ms temperature to reduce the duration of the austenite instability temperature range (between Ar1 and Ms temperatures, typically 650-400℃), thus preventing the transformation of austenite into pearlite. Specifically, quenching oil is used as the quenching fluid, and its temperature is 50 to 60℃.

[0033] The gears of a certain new energy vehicle transmission are made of 18CrNiMo7-6, with a module of 5 and a tip circle diameter of 180mm. The grinding allowance during machining is 0.1mm.

[0034] After conventional carburizing, quenching, tempering, nitriding, and grinding of the gear, the hardness of the carburized layer was tested. The hardness gradient of the carburized layer was 65HRC→35HRC, meaning that the surface hardness of the carburized layer could reach 65HRC and the hardness of the inner layer of the carburized layer could reach 35HRC. The hardness gradient of the carburized layer in the traditional process was (58-62)HRC→30HRC. The hardness of the carburized layer in this invention is improved.

[0035] XRD (X-ray diffraction analysis) of the gears showed that the residual austenite in the carburized layer was less than 5%, which is far lower than that of conventional heat treatment processes (8%-12% residual austenite).

[0036] The tooth profile was inspected for dimensions, and the dimensional error was less than 0.02 mm, which meets the design requirements.

[0037] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A gear pressure quenching device, characterized in that: It includes a horizontal worktable (1), on which a gear tray (2) is provided, and the gear tray (2) is connected to a drive mechanism (3) that drives the gear tray (2) to reciprocate linear motion; The upper surface of the gear tray (2) is provided with a quenching blind hole (4). The diameter of the quenching blind hole (4) is larger than the tooth tip circle diameter of the gear, and the depth of the quenching blind hole (4) is larger than the thickness of the gear. The quenching blind hole (4) is connected to a quenching liquid supply mechanism and a quenching liquid discharge mechanism. A pressure mechanism (11) is provided above the gear tray (2), and the pressure mechanism (11) is connected to a pressure head (12). The diameter of the pressure head (12) is adapted to the diameter of the quenched blind hole (4).

2. The gear pressure quenching device as described in claim 1, characterized in that: The quenching fluid supply mechanism includes a fluid inlet hose (8) installed on the side wall of the quenching blind hole (4), and the fluid inlet hose (8) is connected to the quenching fluid tank (10) via a pump (9).

3. The gear pressure quenching device as described in claim 2, characterized in that: The quenching fluid discharge mechanism includes a drain hole (5), which is connected to a drain hose (7) via an overflow valve (6). The drain hose (7) is connected to the quenching fluid tank (10).

4. The gear pressure quenching device as described in claim 3, characterized in that: The inlet hose (8) and the outlet hole (5) are located on the two side walls of the quenching blind hole (4), and the inlet hose (8) is higher than the outlet hole (5).

5. The gear pressure quenching device as described in claim 1, characterized in that: The bottom wall of the quenching blind hole (4) is provided with a plurality of guide blind holes. A support column (14) that slides with the guide blind hole is provided in the guide blind hole. A spring (15) is provided between the lower end of the support column (14) and the bottom of the guide blind hole.

6. The gear pressure quenching device as described in claim 1, characterized in that: The outer wall of the pressure head (12) is provided with a sealing sleeve (16).

7. The gear pressure quenching device as described in claim 1, characterized in that: The drive mechanism (3) is a hydraulic cylinder.

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