Hot forming process of high-temperature bearing steel flange forge piece

Abstract

The invention discloses a hot forming process of a high-temperature bearing steel flange forge piece, which comprises the following steps of: taking a high-temperature bearing steel material as a raw material, performing heat treatment, performing extrusion forming in an extrusion die by adopting a press machine, and finally performing punching and annealing treatment to obtain a flange forge piece finished product. By the adoption of the hot forming process, according to the machining capacity of existing equipment, a high-temperature bearing steel material serves as a raw material, a die pressing product is formed through extrusion of a 250T press machine by adopting a closed extrusion forming process after homogenization treatment is conducted, then a stamping product is formed through stamping of a punching die, and finally annealing treatment is conducted. According to the technical scheme, the 8Cr4Mo4V high-temperature bearing steel can be subjected to hot pressing forming treatment, the production efficiency can be improved, the forging quality can be improved, the raw material utilization rate can be increased, and the production cost is greatly reduced, so that the machined product meets the technical requirements of flange forgings, a new machining idea is provided for machining of small flange forgings, and the method is suitable for application and popularization.

Description

Technical Field

[0001] The invention relates to the technical field of bearing supporting product processing, and in particular to a hot forming process for a high-temperature bearing steel flange forging. Background Art

[0002] With the rapid development of my country's aviation industry, high-end aviation parts have become a key factor restricting its development, and higher requirements have been put forward for the raw materials used in parts. In order to meet the complex and harsh working environment of aviation bearings, a variety of bearing materials have been developed at home and abroad. Since bearings are important components of the engine system, they are closely related to the performance, life and reliability of the engine. Their service conditions are complex and have the characteristics of high temperature, high speed and heavy load. As a supporting product of bearings, flanges are widely used.

[0003] like Figure 1 As shown in the figure, a small flange forging is required to match the bearing of a certain military model. It is not only small in size, but also requires high processing accuracy. The material required for the forging is 8Cr4Mo4V high-temperature bearing steel material, and its process is specified as 750 kg hammer processing (die forging forming forging). This product is processed by the existing hammer die forging, and there are mainly four problems: First, according to the characteristics of the hammer forging die, the die hardness is preferably controlled at HRC42-46. During long-term use, the die is prone to deformation, resulting in unstable forging quality, especially the small outer diameter of the forging is not perpendicular to the plane, which makes lathe processing and clamping difficult; second, the die loss is large, and on average each forming die can only make about 10 forgings before it will deform, resulting in large die consumption; third, the existing hammer forging method, according to the process characteristics of hammer forging, results in a large forging reserve, resulting in a high process quota and material waste; fourth, the use of hammer forging requires many operators and there is also a problem of high labor intensity.

[0004] As the company's order quantity for such small flange bearing products continues to increase, resulting in an increasing demand for forgings, the existing hammer forging method not only has low production efficiency, but also has unstable quality. Therefore, in order to improve production efficiency, improve forging quality, improve material utilization, and reduce production costs, it is necessary to improve the existing forming process according to the existing equipment capabilities, thereby providing a different from the existing forming process, using a 250T press, adopting a closed extrusion forming process, and realizing hot forming, thereby meeting the processing needs of flange forgings. Summary of the invention

[0005] The technical problem to be solved by the present invention is to address the problems existing in the background technology. In order to meet the processing requirements of small flange forgings, the existing 250T press is used and a closed extrusion molding process is adopted to realize hot pressing forming of 8Cr4Mo4V high-temperature bearing steel, thereby meeting the processing requirements of flange forgings. Specifically, it is a hot forming process for high-temperature bearing steel flange forgings.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a hot forming process of a high-temperature bearing steel flange forging, wherein the hot forming process uses a high-temperature bearing steel material as a raw material, after heat treatment, uses a press to extrude and form in an extrusion die, and finally punches and anneals to obtain a flange forging finished product. The specific hot forming process includes the following steps; S1. sawing material: using 8Cr4Mo4V high temperature bearing steel material with a diameter of φ32mm, sawing material according to the specified process cutting weight to obtain blanks; S2. Heating: The blank obtained in step S1 is first preheated at a temperature of 800 to 850°C for 32 to 60 minutes, and then the preheated blank is transferred to a high temperature furnace for high temperature heating at a temperature of 1060 to 1120°C for 22 to 60 minutes; S3. Upsetting cake: The blank obtained in step S2 is forged, upsetting into a cake shape using a press, and controlling the height of the upsetting cake to obtain an upsetting material; S4 extrusion molding: The upsetting material obtained in step S3 is put into a closed extrusion mold, and the upsetting material is molded by a press to obtain a molded product; S5. Punching: The molded product obtained in step S4 is placed in a punching die, and is formed by stamping with a press to obtain a stamped product; S6. Slow cooling in furnace: put the stamping product obtained in step S4 into a heating furnace for heating, the heating temperature is 300-500°C, and the heating time is 120-180 minutes; annealing: then annealing treatment is performed, the annealing temperature is 900-950°C, and the insulation time is 6-9 hours; after annealing treatment, take it out of the furnace and slowly cool it at room temperature to obtain the desired flange forging finished product.

[0007] Furthermore, a hot forming process for a high-temperature bearing steel flange forging described in the present invention is adopted. In the sawing process of step S1, a high-temperature bearing steel round material with a diameter of φ32 mm is used as the raw material, the cutting weight is 248±6g, and the sawing length is 38.8mm, so as to obtain a blank.

[0008] Furthermore, a hot forming process for a high-temperature bearing steel flange forging described in the present invention is adopted. During the heating process of step S2, the preheating treatment of step S2 adopts a medium frequency induction furnace, the preheating temperature is 830-850°C, and the preheating time is 32 minutes, while the heating temperature of the high-temperature furnace is 1080±20°C, and the heating time is 22 minutes.

[0009] Furthermore, a hot forming process for a high-temperature bearing steel flange forging described in the present invention is adopted. In the step S3 upsetting process, a 250T press is used to forge the blank, and the height of the upsetting is controlled to be 24 mm, ensuring that the verticality of the end face of the upsetting is ≤1 degree.

[0010] Furthermore, a hot forming process for a high-temperature bearing steel flange forging described in the present invention is adopted. During the extrusion molding process in step S4, the upsetting material is put into a closed extrusion molding die, and a die head with a diameter of φ28 mm is used. A 250T press is used to mold the upsetting material once to ensure that the verticality of the end face of the forging is ≤1 degree, so as to obtain a molded product.

[0011] Furthermore, a hot forming process for a high-temperature bearing steel flange forging described in the present invention is adopted. During the punching process of step S5, the molded product is placed in a punching die, and a punch with a diameter of φ28 mm is used. A 250T press is used to punch the molded product once to obtain a stamped product.

[0012] Furthermore, a hot forming process for a high-temperature bearing steel flange forging described in the present invention is adopted. During the slow cooling process in the furnace in step S6, the heating furnace adopts an induction heating furnace, the heating temperature is 380-420°C, and the heating time is 120 minutes; then annealing treatment is performed, the annealing temperature is 915-925°C, and the insulation time is 7.5-8.5 hours; after annealing treatment, the flange forging is taken out from the furnace and slowly cooled at room temperature to obtain the desired flange forging product.

[0013] Compared with the prior art, the hot forming process of the high-temperature bearing steel flange forgings disclosed in the present invention has the following beneficial effects: before extrusion molding, the upsetting material is forged to meet the height after being heated for homogenization. Compared with the existing hammer forging method, the retention amount of the forging can be reduced, thereby reducing the material cost; and during the extrusion molding process, the upsetting material is put into a closed extrusion molding die, and the upsetting material is molded once by a 250T press, which can not only improve the production efficiency but also improve the quality of the forgings. After extrusion molding, a matching punch is used, and a 250T press is used for stamping and molding once, and finally annealing treatment is performed. By controlling the temperature and time of the annealing process, the purpose of affecting the flange structure is achieved, and the uneven distribution of stress is eliminated or reduced, thereby achieving the purpose of reducing the change in flange size.

[0014] It can be seen that by adopting the hot forming process described in the present invention, according to the processing capacity of existing equipment, high-temperature bearing steel material is used as raw material, first through homogenization treatment, and then a closed extrusion molding process is adopted, and it is extruded into a molded product by a 250T press, and then through a punching die, it is stamped into a stamped product, and finally annealed. It can not only realize the hot pressing forming treatment of 8Cr4Mo4V high-temperature bearing steel, but also improve production efficiency, improve forging quality, improve raw material utilization, and greatly reduce production costs, so that the processed products meet the technical requirements of flange forgings, and provide a new processing idea for the processing of small flange forgings, which is suitable for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0016] Figure 1 It is a structural schematic diagram of the flange to be processed according to the present invention; Figure 2 It is a schematic structural diagram of the closed extrusion molding die of the present invention; Figure 3 It is a schematic structural diagram of the punching die of the present invention; Figure 4 This is a schematic diagram of the structure of the flange forging during the forging process. DETAILED DESCRIPTION

[0017] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0018] like Figures 2 to 4 As shown, this embodiment provides a hot forming process for a high-temperature bearing steel flange forging. The hot forming process uses a high-temperature bearing steel material as a raw material, and after heat treatment, a press is used to extrude the material in an extrusion die, and finally punching and annealing are performed to obtain a flange forging finished product. The specific hot forming process includes the following steps; S1. Saw material: 8Cr4Mo4V high temperature bearing steel material with a diameter of φ32mm is used as the raw material, and the material weight is set to 248±6g for sawing, and the sawing length is 38.8mm, that is, the blank is obtained; S2. Heating: The blank obtained in step S1 is first preheated in a medium frequency induction furnace at a preheating temperature of 800°C for 35 minutes, and then the preheated blank is transferred to a high temperature furnace for high temperature heating at a heating temperature of 1060°C for 25 minutes; S3. Upsetting cake: The blank obtained in step S2 is forged, and the blank is forged using a 250T press, upsetting into a cake shape, and controlling the height of the upsetting cake to be 24mm, ensuring that the verticality of the end face of the upsetting cake is ≤1 degree, and obtaining the upsetting material; S4 extrusion molding: The upsetting material obtained in step S3 is put into a closed extrusion mold, using a die head with a diameter of φ28mm, and a 250T press is used to press the upsetting material once to ensure that the verticality of the forging end face is ≤1 degree to obtain a molded product; S5. Punching: The molded product obtained in step S4 is placed in a punching die, a punch having a diameter of φ28mm is used, and a 250T press is used to stamp the molded product once to obtain a stamped product; S6. Slow cooling in the furnace: The stamped product obtained in step S4 is placed in an induction heating furnace for heating at a temperature of 300-380°C for 120 minutes; then annealing is performed at a temperature of 900-920°C for 8-9 hours; after annealing, the product is taken out of the furnace and slowly cooled at room temperature to obtain the desired flange forging product. Example 2

[0019] The hot forming process of this embodiment is basically the same as that of embodiment 1, and the differences are mainly in the following aspects: First, in the heating process of step S2: the preheating temperature is 830°C, the preheating time is 32 minutes, and then the preheated blank is transferred into a high temperature furnace for high temperature heating, the heating temperature is 1080°C, and the heating time is 22 minutes; Second, during the slow cooling process in the furnace in step S6: the heating temperature is 380-420°C, and the heating time is 130 minutes; then annealing is performed, the annealing temperature is 915-925°C, and the insulation time is 7.5-8.5 hours; after annealing, it is taken out from the furnace and slowly cooled at room temperature to obtain the desired flange forging product. Example 3

[0020] The hot forming process of this embodiment is basically the same as that of embodiment 1, and the differences are mainly in the following aspects: First, in the heating process of step S2: the preheating temperature is 850°C, the preheating time is 35 minutes, and then the preheated blank is transferred into a high temperature furnace for high temperature heating, the heating temperature is 1120°C, and the heating time is 24 minutes; Second, in the slow cooling process in the furnace in step S6: the heating temperature is 400-500°C, the heating time is 140 minutes; then annealing is performed, the annealing temperature is 925-950°C, and the insulation time is 6-7 hours; after annealing, it is taken out of the furnace and slowly cooled at room temperature to obtain the desired flange forging finished product.

[0021] According to the hot forming process described in Example 2, 20 pieces of a certain type of flange forgings were first produced by trial mold on July 2, 2022. After testing, the quality of the forgings was stable, the characteristics of small outer diameter and large slope of hammer forging were eliminated, the material consumption quota was reduced, and the number of operators and labor intensity were greatly improved. Finally, the hot forming process after process improvement was adopted, and the hot forming process described in Example 2 was adopted. On July 16, 2022, a small batch trial production of 471 pieces of a certain type of flange forgings was carried out. After inspection, the size, hardness, and metallographic structure of the forgings were checked, and all of them met the forging process requirements.

[0022] The improved hot forming process has increased production efficiency by 40% compared with the hammer process (the original hammer output was 550 pieces per shift, and the current press output is 800 pieces per shift). The quota of 1,000 pieces saves 33 kg of material compared with the hammer process, and the labor intensity of workers has been greatly improved. The original 750kg hammer forging process required 10 operators, but now a 250T press, a closed extrusion mold, and the improved hot forming process only require 6 people. The mold loss is significantly reduced, and the overall economic benefits are good.

[0023] In the specific application process, it is only necessary to design in advance the extrusion die, forming die, forming punch, plug and punching die that match the 250T press. The die hardness can be controlled at HRC46-50, and its die hardness is higher than that of the hammer forging die.

[0024] Using the improved hot forming process, from July 16, 2022 to November 30, 2022, a total of five batches of a certain type of flange forgings were processed, totaling 3,267 pieces. Compared with the original process, 107.8 kg of 8Cr4Mo4V raw materials were saved; 119 hours of processing time were saved; mold consumption was greatly reduced, and costs were significantly reduced; the forgings had stable dimensions and good form and position tolerances, which were convenient for subsequent processing, and the overall economic effect was good.

[0025] To sum up, the hot forming process described in the present invention is adopted, according to the processing capacity of existing equipment, with high-temperature bearing steel material as raw material, first through homogenization treatment, adopting closed extrusion molding process, through the existing 250T press extrusion forming into a molded product, and then through a punching die, stamping forming into a stamping product, and finally annealing treatment, which can not only realize the hot pressing forming treatment of 8Cr4Mo4V high-temperature bearing steel, but also improve production efficiency, improve forging quality, improve raw material utilization rate, greatly reduce production costs, so that the processed products meet the technical requirements of flange forgings, forgings for small flange processing provides a new processing idea, suitable for popularization and application.

[0026] Other details of the present invention are conventional technologies known to those skilled in the art and are therefore not described in detail.

[0027] The protection scope of the present invention is not limited to the technical solutions disclosed in the specific implementation methods. The above description is only a preferred implementation method of the present invention and does not limit the present invention. Any minor modifications, equivalent substitutions and improvements made according to the technical solutions of the present invention should be included in the protection scope of the technical solutions of the present invention.

Claims

1. A hot forming process for high temperature bearing steel flange forgings, characterized in that: The hot forming process uses high-temperature bearing steel material as raw material, and after heat treatment, uses a press to extrude it in an extrusion die, and finally punches and anneals it to obtain a flange forging finished product. The specific hot forming process includes the following steps: S1. sawing material: using 8Cr4Mo4V high temperature bearing steel material with a diameter of φ32mm, sawing material according to the specified process cutting weight to obtain blanks; S2. Heating: The blank obtained in step S1 is first preheated at a temperature of 800 to 850°C for 32 to 60 minutes, and then the preheated blank is transferred to a high temperature furnace for high temperature heating at a temperature of 1060 to 1120°C for 22 to 60 minutes; S3. Upsetting cake: The blank obtained in step S2 is forged, upsetting into a cake shape using a press, and controlling the height of the upsetting cake to obtain an upsetting material; S4 extrusion molding: The upsetting material obtained in step S3 is put into a closed extrusion mold, and the upsetting material is molded by a press to obtain a molded product; S5. Punching: The molded product obtained in step S4 is placed in a punching die, and is formed by stamping with a press to obtain a stamped product; S6. Slow cooling in furnace: put the stamping product obtained in step S4 into a heating furnace for heating, the heating temperature is 300-500°C, and the heating time is 120-180 minutes; annealing: then annealing treatment is performed, the annealing temperature is 900-950°C, and the insulation time is 6-9 hours; after annealing treatment, take it out of the furnace and slowly cool it at room temperature to obtain the desired flange forging finished product.

2. The hot forming process of a high temperature bearing steel flange forging according to claim 1, characterized in that: In the sawing process of step S1, a high-temperature bearing steel round material with a diameter of φ32 mm is used as the raw material, the cutting weight is 248±6g, and the sawing length is 38.8mm, so as to obtain a blank.

3. The hot forming process of a high temperature bearing steel flange forging according to claim 1, characterized in that: During the heating process of step S2, the preheating treatment of step S2 adopts a medium frequency induction furnace, the preheating temperature is 830-850°C, the preheating time is 32 minutes, and the heating temperature of the high temperature furnace is 1080±20°C, and the heating time is 22 minutes.

4. The hot forming process of a high temperature bearing steel flange forging according to claim 1, characterized in that: In step S3, during the upsetting process, a 250T press is used to forge the blank, the height of the upsetting is controlled to be 24 mm, and the verticality of the end face of the upsetting is ensured to be ≤1 degree.

5. The hot forming process of a high temperature bearing steel flange forging according to claim 1, characterized in that: In step S4, during the extrusion molding process, the upsetting material is put into a closed extrusion molding die, and a die head with a diameter of φ28 mm is used to press the upsetting material once using a 250T press to ensure that the verticality of the end face of the forging is ≤1 degree to obtain a molded product.

6. The hot forming process of a high temperature bearing steel flange forging according to claim 1, characterized in that: In the punching process of step S5, the molded product is placed in a punching die, and a punch with a diameter of φ28 mm is used to punch the molded product once using a 250T press to obtain a stamped product.

7. The hot forming process of a high temperature bearing steel flange forging according to claim 1, characterized in that: During the slow cooling process in the furnace in step S6, the heating furnace adopts an induction heating furnace, the heating temperature is 380-420°C, and the heating time is 120 minutes; then annealing treatment is performed, the annealing temperature is 915-925°C, and the insulation time is 7.5-8.5 hours; after annealing treatment, it is taken out from the furnace and slowly cooled at room temperature to obtain the desired flange forging finished product.

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