Bevel gear pressure quenching device and heat treatment deformation control method

Abstract

The application provides a bevel gear pressure quenching device and a heat treatment deformation control method. The device comprises: a support base, which is a connecting part suitable for a quenching machine tool; a support ring, which is connected with the support base, and the upper surface of the support ring is provided with an angle compensation; a spline mandrel, the lower end of which is connected with a machine tool center positioning; an upper mandrel, one end of which is embedded in the interior of the spline mandrel for centering and supporting the upper shaft diameter of a part; a support plate, which is provided with a multi-stage different height structure; an upper pressing ring, which is used for controlling the surface cone angle of the part; the inner cone angle of the contact position between the upper pressing ring and the part is compared with the surface cone angle of the part, and an angle compensation is set; an upper pressing head, which passes through the upper pressing ring to limit the load of the upper shaft end of the part, and presses the lower shaft shoulder of the part against the upper surface of the support plate; and the method can effectively avoid the out-of-tolerance of the oval, warping and bevel gear root cone height of the part after heat treatment, and has a good shape correction effect.

Description

Technical Field

[0001] This application belongs to the field of deformation control technology for carburizing and quenching heat treatment of bevel gear parts, and particularly relates to a pressure quenching device and a heat treatment deformation control method for bevel gears. Background Technology

[0002] Currently, an aviation product involves a type of 9310 steel carburized bevel gear. The entire unit weighs over 40 tons, and the 12000kW-class torque-split transmission system it employs has low technological maturity. Considering the high power, high transmission efficiency, and high reliability requirements of the input and driven bevel gears in the transmission system's main reducer, the load-bearing gear is designed as a large-face cone-angle spiral bevel gear shaft structure. The tooth tip circle diameter is φ544mm, the face cone angle is 69°83′, the web bevel wall thickness is 9.4mm, and the total height of the part is 293mm. The inner shaft (with internal splines) is connected to the outer bevel gear through a thin-walled bevel web. The part is carburized at four locations (both ends of the shaft diameter and shoulder, the internal spline, and the outer bevel gear). The carburizing requirements for the internal spline differ from those for the outer bevel gear and shaft diameter, requiring two carburizing processes. The grinding allowance after carburizing is ≤0.25mm. The structural features such as large diameter-to-thickness ratio, large size, large taper angle, and multi-zone carburizing make the heat treatment process control more complicated. In order to ensure that the final carburized layer in each carburized area of ​​the product meets the requirements, the requirements for pre-grinding dimensional control and heat treatment deformation state must reach a high level. Summary of the Invention

[0003] The purpose of this invention is to provide a device for adapting spiral bevel gear shafts with large diameter-to-thickness ratios, large dimensions, large facet cone angles, and multi-region carburized structures, and a method for controlling heat treatment deformation using this device on a HEESS SP1250 quenching press. This method has a significant effect on controlling quenching deformation of spiral bevel gear shafts with thin webs, large facet cone angles, and multi-region carburized structures with diameters ≥500mm. It can effectively avoid elliptical shapes, warping, and deviations in bevel tooth root cone height after heat treatment, and has a very good shape correction effect.

[0004] In a first aspect, this application provides a pressure quenching apparatus for bevel gears, the apparatus comprising: The support base is the connection part for adapting to the HEESS SP1250 quenching machine tool; A support ring is connected to the support base and is used to support the part; the upper surface of the support ring is provided with angle compensation. Splined mandrel, the lower end of which is connected to the center of the machine tool for positioning; The upper spindle is embedded at one end inside the spline spindle for centering and to support the upper diameter of the part; The support plate is designed with multiple levels of different heights to be adapted to the changes in shaft diameter length during the part quenching process. The relative height from the shaft shoulder to the back of the tooth plane after the part is quenched is determined by the relative height of the upper surface of the support plate and the support ring. The upper pressure ring is used to control the cone angle of the part surface; the cone angle at the contact position between the upper pressure ring and the part is compensated compared with the set cone angle of the part surface. The upper pressure head passes through the upper pressure ring to limit the load on the upper shaft end of the part, and presses the lower shaft shoulder of the part against the upper surface of the support plate.

[0005] Preferably, the inner cone angle at the contact position between the upper pressure ring and the part is compensated by 2 degrees compared to the surface cone angle of the part.

[0006] Preferably, the upper surface of the support ring is provided with the same angle compensation as the upper pressure ring.

[0007] Preferably, the spline mandrel has a hollow structure in the middle.

[0008] Preferably, the device further includes: The fixing plate is connected to the upper end of the upper pressure head by a second screw; The spindle support is mounted on the machine tool to support the splined spindle.

[0009] Preferably, the device further includes: The pressure head can be disassembled by applying a disassembly force to the upper mandrel and the spline mandrel through the hollow part of the upper pressure head; A disassembly disc, mounted on the upper spindle, is used for disassembling parts.

[0010] Secondly, this application also provides a method for controlling heat treatment deformation, the method comprising: The carburized gears after high-temperature tempering are quenched. The quenching heating is carried out in a rotary hearth furnace, and the quenching cooling is carried out in a quenching device adapted to the HEESS SP1250 pressure quenching machine. During the cooling process, the quenching oil is only sprayed into the center, and then diffuses and overflows from the center to the top and the outer periphery. The purpose is to cool the shaft diameter part first, so as to better play the centering role of the spline mandrel. Before the quenching oil spray, the machine tool punch is loaded with a delay of about 15 seconds. The purpose is to allow the part to receive the correction effect of the upper pressure ring of the tooling by the cone angle while it is red-hot. After the delay, the punch and the upper pressure ring are loaded at the same time. The punch is loaded with a fixed load, and the upper pressure ring is loaded with a pulsating load until the quenching and cooling is completed. The quenched gears are then subjected to deep cryogenic treatment. The gears that have undergone cryogenic treatment are subjected to low-temperature tempering.

[0011] Preferably, before quenching the carburized gear after high-temperature tempering, the process further includes: Carburized gears are pretreated by normalizing, quenching, and tempering. The carburized gear was placed in a controlled atmosphere furnace for carburizing. The holding temperature was 927±6℃, and the carbon potential in the strong carburizing section was 1.1±0.05%C and 0.98±0.05%C. After carburizing, the furnace was cooled down to a holding temperature of 815±14℃ with a carbon potential of 0.9±0.05%C. After holding for 30±10 minutes, a protective atmosphere was applied for cooling. High-temperature tempering was carried out within 5 hours after carburizing. Gears that have undergone controlled atmosphere carburizing are subjected to high-temperature tempering. High-temperature tempering can effectively release internal stress in the parts, improve the microstructure, and eliminate residual austenite after quenching.

[0012] The beneficial technical effects of this application are as follows: This invention provides a method for controlling the deformation of a spiral bevel gear shaft with a large diameter-to-thickness ratio, large dimensions, large taper angle, and multi-region carburized structure during carburizing and quenching. By applying a precision-sized limiting quenching fixture, pre-setting the angle compensation between the pressure ring and the support ring, using a spline mandrel for centering support, setting the relative height of the upper surface of the support plate and the support ring in stages, and combining the application of punch loading delay and upper pressure ring loading pulsation, the deformation of the part during heat treatment is effectively controlled, providing a reference for other similar structural parts. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the structure of a large-size bevel gear pressure quenching device provided in the embodiments of this application; Figure 2 This is a schematic diagram of a φ544mm thin-walled inclined web spiral bevel gear shaft structure provided in an embodiment of this application; Wherein: 1-Upper pressure ring; 2-Support base; 3-Splined mandrel; 4-Support plate; 5-First screw; 6-Upper mandrel; 7-Upper pressure head; 8-Fixing plate; 9-Second screw; 10-Disassembly pressure head; 11-Disassembly disc; 12-Disassembly base; 14-Mandrel support; 15-Support ring; 16-Third screw. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0017] In the description of this invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing and simplifying the invention, and should not be construed as limiting the invention. Furthermore, the use of ordinal numbers (e.g., "first and second," etc.) is for distinguishing objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0018] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly, encompassing both direct connection and indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0019] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] The following describes the embodiments and appendices. Figure 1 -Appendix Figure 2 The present invention will be described in further detail, but the embodiments of the present invention are not limited thereto.

[0021] The device provided in this application mainly consists of an upper pressure ring 1, a support base 2, a spline mandrel 3, a support plate 4, an upper spindle 6, an upper pressure head 7, and a support ring 15. The inner cone angle of the upper pressure ring 1 at the contact position with the part is compensated by 2 degrees compared to the surface cone angle of the part (part surface cone angle 69.826°, upper pressure ring inner cone angle 67.826°). Its main purpose is to compensate for the tooth angle deflection caused by the shortening of the shaft diameter during the part's quenching process. The upper pressure ring primarily controls the surface cone angle of the part. The support base and support ring are connected as a single unit. The support base is adapted to HEESS. The connecting part of the SP1250 quenching press has a support ring that supports the part. The upper surface of the support ring is also designed with the same angle compensation as the upper pressure ring (changing from a planar structure to an umbrella-shaped structure with an angle of 2 degrees with the plane). The spline mandrel has a hollow structure in the middle, with its lower end connected to the machine tool center and its upper end connected to the upper mandrel. It supports the spline and also serves to center the part during quenching. The support plate has multiple height structures to adapt to the changes in shaft diameter length during the part quenching process. The relative height from the shaft shoulder to the back of the tooth after quenching is determined by the relative height of the upper surfaces of the support plate 4 and the support ring 15. The parallelism and flatness of the upper surfaces of the support plate 4 and the support ring must be strictly guaranteed. The upper mandrel is embedded inside the spline mandrel for centering and supports the upper shaft diameter of the part. The upper pressure head 7 limits the load on the upper shaft end of the part and presses the lower shaft shoulder of the part against the upper surface of the support plate. When using the above-mentioned quenching fixture to control the quenching deformation of spiral bevel gear shafts with large diameter-to-thickness ratio, large size, large face cone angle, and multi-area carburizing structure, it should be ensured that the upper and lower fixtures of the HEESS SP1250 quenching press are concentric and the offset does not exceed 0.03mm.

[0022] In other embodiments of this application, a method for controlling the quenching deformation of a spiral bevel gear shaft with a large diameter-to-thickness ratio, large dimensions, large taper angle, and multi-region carburized structure is also provided, including the following steps: S1. Perform normalizing, quenching and tempering pretreatment on carburized gears; S2. The carburized gear is placed in a controlled atmosphere furnace for carburizing. The holding temperature is 927±6℃, with carbon potentials of 1.1±0.05%C and 0.98±0.05%C in the strong carburizing section. After carburizing, the furnace is cooled down to a holding temperature of 815±14℃, with a carbon potential of 0.9±0.05%C. After holding at this temperature for 30±10 minutes, a protective atmosphere is applied for cooling. High-temperature tempering is performed within 5 hours after carburizing. S3. The gears after controlled atmosphere carburizing are subjected to high-temperature tempering. High-temperature tempering can effectively release the internal stress of the parts, improve the microstructure, and eliminate residual austenite after quenching. S4. The carburized gear after high-temperature tempering is quenched. The quenching heating is carried out in a rotary hearth furnace, and the quenching cooling is carried out using a quenching fixture adapted to the HEESS SP1250 pressure quenching machine. This fixture is composed of the above-mentioned integral precision dimensional limiting parts. During the part cooling process, the quenching oil is only sprayed at the center, and it diffuses and overflows from the center to the top and the outer periphery. The purpose is to cool the shaft diameter part of the part first, so as to better play the centering role of the spline mandrel. Before the quenching oil spray, the machine tool punch is loaded with a delay of about 15 seconds. The purpose is to allow the part to receive the correction effect given by the upper pressure ring of the fixture by the cone angle in the red-hot state. After the delay, the punch and the upper pressure ring are loaded at the same time. The punch is a fixed load, and the upper pressure ring is a pulsating load until the quenching and cooling is completed. S5. Perform deep cryogenic treatment on the quenched gears. S6. Perform low-temperature tempering on the gears after cryogenic treatment.

[0023] As a further improvement to the above technical solution: Optionally, a compensation allowance can be set for the relative height between the shaft shoulder and the back of the tooth plane before heat treatment of the part, reducing the weakening of tooling control effect caused by shaft diameter shortening.

[0024] This invention provides a method for controlling the deformation of a spiral bevel gear shaft with a large diameter-to-thickness ratio, large dimensions, large taper angle, and multi-region carburized structure during carburizing and quenching. By applying a precision-sized limiting quenching fixture, pre-setting the angle compensation between the pressure ring and the support ring, using a spline mandrel for centering support, setting the relative height of the upper surface of the support plate and the support ring in stages, and combining the application of punch loading delay and upper pressure ring loading pulsation, the deformation of the part during heat treatment is effectively controlled, providing a reference for other similar structural parts.

[0025] In other embodiments of this application: the driven bevel gear structure for a certain material input is a thin-walled helical bevel gear shaft structure with a φ544mm diameter inclined web (see...). Figure 2 The inner shaft (with internal splines) and outer bevel gear are connected by a thin-walled inclined web. The part undergoes carburizing at four locations, with a required carburizing depth of 1.7–1.9 mm (measured to HV513). The effective depth of the tooth root is allowed to be 20% lower than the measured value at the middle of the tooth height. The carburizing depth at the tooth tip is measured. The carburizing depth at HRC60 on the tooth surface is ≥0.76 mm (excluding the tooth root), and the depth at HRC60 on the tooth root and fillet is ≥0.61 mm. After carburizing, the maximum allowable machining allowance on the tooth surface and tooth root is 0.2 mm, and the maximum allowable machining allowance on other surfaces is 0.25 mm. After heat treatment, the part should achieve an ellipticity within 0.2 mm, an overall end face warpage within 0.1 mm, and relative dimensions such as the root cone height meet machining requirements.

[0026] This embodiment provides a method for controlling the quenching deformation of a spiral bevel gear shaft with a large diameter-to-thickness ratio, large size, large taper angle, and multi-regional carburizing structure, which specifically includes the following steps: (1) The shoulder height of the part is compensated with a margin of 0.4mm before heat treatment. All areas outside the carburized area are protected by copper plating with a copper layer thickness of 0.04mm. (2) Use a sandblasting machine to clean the carburized surface of the parts. The sandblasting pressure is 0.2 MPa. Carburizing should be carried out within 1 hour after sandblasting. (3) Carburizing was performed using a controlled atmosphere double-chamber carburizing furnace: the temperature was 927℃, the carbon potential of stage I was 0.35%C, and the carburizing time was 35min; the carbon potential of stage II was 1.1%C, and the time was 9h; the carbon potential of stage III was 0.98%C, and the time was 6h; the carbon potential of stage IV was 0.95%C, and the time was 2h. After carburizing, the furnace was moved to another heating chamber, and the holding temperature was 815℃, the carbon potential was 0.9%C, and the holding time was 30min. Nitrogen gas was then used for cooling. High-temperature tempering was performed 3h after carburizing. (4) Use a protective atmosphere furnace for high-temperature tempering, hold at 621°C for 195 minutes, and then cool with nitrogen. (5) Remove the copper layer and oxide scale from the surface of the parts; (6) The parts and samples are plated with copper as a whole, with a copper layer thickness of 0.02 mm; (7) The parts were quenched using an RDES-230CN rotary hearth furnace for heat preservation, and oil cooling was performed using a HEESS SP1250 pressure quenching machine tool with a special pressure quenching fixture (1B412 / XX-4013). The quenching holding temperature was 820℃, the holding time was 90min, the reference carbon potential was 0.5%C, the quenching oil temperature was 60℃, and the quenching cooling time was 480s. After the heat preservation was completed, the parts were transferred to the fixture of the pressure quenching machine tool 15s later. The inner ring pressure of the machine tool was set to 70bar, the punch pressure was set to 40bar, the inner ring pressure pulsation pressurization time was 7s, the pause pulsation pressurization time was 2s, the punch pressure delay was 15s, the quenching oil flow rate was 3000L / min at the core, and the flow rate in the middle and outside was 0. The fixture structure is shown in the appendix. Figure 1 ; (8) Deep cryogenic treatment at -80℃ for 4.5 hours, followed by tempering within 3 hours after cryogenic treatment; (9) Temper at 150℃ for 4 hours, then air cool; (10) Remove the copper layer and oxide scale from the surface of the parts; (11) Remove hydrogen at 140℃ for 5.5 hours, then air cool; (12) Dimensional inspection.

[0027] The measured values ​​after completion are as follows: 1. The carburization depth of the tooth is 1.89mm (measured to HV513), the carburization layer depth at HRC60 is 1.13mm, the carburization layer depth at the tooth root and fillet at HRC60 is 1.51mm, and the carburization layer depth at the tooth root and fillet at HRC60 is 0.9mm. 2. External tooth ellipse 0.19mm, end face warping 0.1mm.

[0028] The conclusion is satisfactory.

[0029] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A pressure quenching device for bevel gears, characterized in that, The device includes: The support base is the connection part for adapting to the HEESS SP1250 quenching machine tool; A support ring is connected to the support base and is used to support the part; the upper surface of the support ring is provided with angle compensation. Splined mandrel, the lower end of which is connected to the center of the machine tool for positioning; The upper spindle is embedded at one end inside the spline spindle for centering and to support the upper diameter of the part; The support plate is designed with multiple levels of different heights to be adapted to the changes in shaft diameter length during the part quenching process. The relative height from the shaft shoulder to the back of the tooth plane after the part is quenched is determined by the relative height of the upper surface of the support plate and the support ring. The upper pressure ring is used to control the cone angle of the part surface; the cone angle at the contact position between the upper pressure ring and the part is compensated compared with the set cone angle of the part surface. The upper pressure head passes through the upper pressure ring to limit the load on the upper shaft end of the part, and presses the lower shaft shoulder of the part against the upper surface of the support plate.

2. The apparatus according to claim 1, characterized in that, The inner cone angle at the contact position between the upper pressure ring and the part is compensated by 2 degrees compared to the surface cone of the part.

3. The apparatus according to claim 2, characterized in that, The upper surface of the support ring is provided with the same angle compensation as the upper pressure ring.

4. The apparatus according to claim 1, characterized in that, The spline mandrel has a hollow structure in the middle.

5. The apparatus according to claim 1, characterized in that, The device further includes: The fixing plate is connected to the upper end of the upper pressure head by a second screw; The spindle support is mounted on the machine tool to support the splined spindle.

6. The apparatus according to claim 1, characterized in that, The device further includes: The pressure head can be disassembled by passing through the hollow part of the upper pressure head and applying a disassembly force to the upper mandrel and the spline mandrel; A disassembly disc, mounted on the upper spindle, is used for disassembling parts.

7. A method for controlling deformation during heat treatment, characterized in that, The method includes: The carburized gears after high-temperature tempering are quenched. The quenching heating is carried out in a rotary hearth furnace, and the quenching cooling is carried out in a quenching device adapted to the HEESS SP1250 pressure quenching machine. During the cooling process, the quenching oil is only sprayed into the center, and then diffuses and overflows from the center to the top and the outer periphery. The purpose is to cool the shaft diameter part first, so as to better play the centering role of the spline mandrel. Before the quenching oil spray, the machine tool punch is loaded with a delay of about 15 seconds. The purpose is to allow the part to receive the correction effect of the upper pressure ring of the tooling by the cone angle while it is red-hot. After the delay, the punch and the upper pressure ring are loaded at the same time. The punch is loaded with a fixed load, and the upper pressure ring is loaded with a pulsating load until the quenching and cooling is completed. The quenched gears are then subjected to deep cryogenic treatment. The gears that have undergone cryogenic treatment are subjected to low-temperature tempering.

8. The method according to claim 1, characterized in that, Before quenching the carburized gear after high-temperature tempering, the process also includes: Carburized gears are pretreated by normalizing, quenching, and tempering. The carburized gear was placed in a controlled atmosphere furnace for carburizing. The holding temperature was 927±6℃, and the carbon potential in the strong carburizing section was 1.1±0.05%C and 0.98±0.05%C. After carburizing, the furnace was cooled down to a holding temperature of 815±14℃ with a carbon potential of 0.9±0.05%C. After holding for 30±10 minutes, a protective atmosphere was applied for cooling. High-temperature tempering was carried out within 5 hours after carburizing. Gears that have undergone controlled atmosphere carburizing are subjected to high-temperature tempering. High-temperature tempering can effectively release internal stress in the parts, improve the microstructure, and eliminate residual austenite after quenching.

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