An induction hardening and tempering method for a main bearing race and the resulting product

Abstract

The present invention relates to the technical field of heat treatment of main bearing rings, and particularly relates to an induction hardening and tempering method for main bearing rings and the obtained products. The products are prepared by this method. The method includes installing the workpiece; installing the first inductor and the second inductor; setting the hardening parameters and completing the induction hardening treatment of the currently to-be-hardened surface of the workpiece; setting the tempering parameters and completing the induction tempering treatment of the currently to-be-hardened surface of the workpiece; a spray cooling treatment of the workpiece is also included between the induction hardening treatment and the induction tempering treatment; the induction hardening treatment and the induction tempering treatment are used in combination to sequentially complete the hardening and tempering operations of the next to-be-hardened surface of the workpiece, and so on, until the hardening and tempering operations of all the to-be-hardened surfaces of the workpiece are completed. The present invention can solve the problems of low production efficiency, high energy consumption and high cost caused by the need for timely tempering in the existing surface hardening treatment method.

Description

Technical Field

[0001] The present invention relates to the technical field of heat treatment of main bearing rings, and particularly relates to an induction quenching and tempering method for main bearing rings and the obtained products. Background Art

[0002] As a core component of a shield machine, the main bearing has the characteristics of high load-bearing capacity, high cost, and difficult replacement. As the main component of the main bearing of the shield machine, the raceway and the rib of the ring need to be quenched to improve the surface hardness of the ring, thereby improving its fatigue life.

[0003] At present, the surface quenching treatment method is generally adopted for the raceway and rib of the main bearing ring, specifically the scanning surface quenching method; after quenching, tempering needs to be carried out in a timely manner (this tempering is a conventional tempering, that is, the single tempering time is usually 7-15 hours, and the single tempering requires nearly 10,000 yuan of electricity cost); if tempering is not carried out in a timely manner, cracks may occur on its surface, resulting in the scrapping of the ring. The ring is expensive, often hundreds of thousands or even millions. If cracks occur, it will cause great economic losses. In addition, since there are generally 3-5 quenching surfaces on the ring, if tempering is carried out in a timely manner every time the surface is quenched, multiple temperings are required; if the ring is heat-treated in this way, not only the production efficiency is low, the labor is wasted, but also a large amount of energy is consumed, increasing the production cost.

[0004] To solve the above problems, it is necessary to develop an induction quenching and tempering method for main bearing rings and the obtained products to solve the problems of low production efficiency, high energy consumption, and high cost caused by the need for timely tempering in the existing surface quenching treatment method. Summary of the Invention

[0005] The purpose of the present invention is to provide an induction quenching and tempering method for main bearing rings and the obtained products, and the specific technical solutions are as follows:

[0006] In the first aspect, the present invention provides an induction quenching and tempering method for main bearing rings, including:

[0007] Step S1, installing the workpiece; hoisting the workpiece onto the workbench of the quenching machine tool, and after aligning the workpiece, clamping the workpiece;

[0008] Step S2, installing the first inductor and the second inductor; arranging the first inductor and the second inductor in sequence along the rotation direction of the workpiece;

[0009] Step S3: Set the quenching parameters and complete the induction quenching treatment of the currently to-be-quenched surface of the workpiece; on the quenching machine tool, set the speed of the workbench driving the workpiece to rotate as 100 - 200 mm / min; set the working power of both the first inductor and the second inductor as 60 - 80 kW; set the working frequency of both the first inductor and the second inductor as 2.0 - 4.0 kHz; set the coupling gap between the first inductor and the workpiece and the coupling gap between the second inductor and the workpiece as 2 - 4 mm; after setting the quenching parameters, start the quenching machine tool, the first inductor and the second inductor to complete the induction quenching treatment of the currently to-be-quenched surface of the workpiece;

[0010] Step S4: Set the tempering parameters and complete the induction tempering treatment of the currently to-be-quenched surface of the workpiece; on the quenching machine tool, set the speed of the workbench driving the workpiece to rotate as 80 - 140 mm / min; set the working power of both the first inductor and the second inductor as 20 - 35 kW; set the working frequency of both the first inductor and the second inductor as 1.0 - 2.0 kHz; set the coupling gap between the first inductor and the workpiece and the coupling gap between the second inductor and the workpiece as 2 - 4 mm; after setting the tempering parameters, start the quenching machine tool, the first inductor and the second inductor to complete the induction tempering treatment of the currently to-be-quenched surface of the workpiece;

[0011] Between the induction quenching treatment and the induction tempering treatment, a spray cooling treatment of the workpiece is also included;

[0012] Step S5: Combine the induction quenching treatment and the induction tempering treatment to sequentially complete the quenching and tempering operations of the next to-be-quenched surface of the workpiece, and so on until the quenching and tempering operations of all to-be-quenched surfaces of the workpiece are completed.

[0013] Optionally, the coolant used in the spray cooling treatment includes PAG quenching liquid; the mass concentration of the PAG quenching liquid used is 10% - 15%, and the flow rate is 60 - 70 L / min.

[0014] Optionally, the spray mode used in the spray cooling treatment is the jet mode.

[0015] Optionally, the jet mode is completed by using a spray box; along the rotation direction of the workpiece, the spray box is arranged behind the second inductor, and inclined spray holes are arranged on the spray box; the inclination direction of the spray holes deviates from the second inductor, and the included angle between its inclination direction and the workpiece surface is 10° - 60°.

[0016] Optionally, the first inductor and the second inductor have the same structure, and both include a magnetic conductor and an induction coil; the magnetic conductor is a rectangular structure with an opening; the induction coil is a hollow rectangular copper tube; the magnetic conductor is integrally embedded in the induction coil.

[0017] Optionally, the induction hardening treatment and the induction tempering treatment further include a circulating cooling treatment for the first inductor and the second inductor.

[0018] Optionally, the circulating cooling treatment includes passing circulating cooling water into the induction coil.

[0019] Optionally, the workpiece is a main bearing race.

[0020] In a second aspect, the present invention provides a product prepared by using the method for induction hardening and tempering of a main bearing race.

[0021] Optionally, the average depth of the hardened layer in the middle of the raceway of the product is 9.7 - 10.1 mm, the average surface hardness after hardening is 60.9 - 61.3 HRC, and the average surface hardness after tempering is 60.3 - 60.8 HRC.

[0022] Applying the technical solution of the present invention has at least the following beneficial effects:

[0023] (1) The method for induction hardening and tempering of a main bearing race provided by the present invention can solve the problems of low production efficiency, high energy consumption, and high cost caused by the need for timely tempering in the existing surface hardening treatment method. Specifically, the present invention first combines the induction hardening treatment and the induction tempering treatment to sequentially complete the hardening and tempering operations on the currently to-be-hardened surface of the workpiece, and then combines the induction hardening treatment and the induction tempering treatment to sequentially complete the hardening and tempering operations on the next to-be-hardened surface of the workpiece, and so on, until the hardening and tempering operations on all to-be-hardened surfaces of the workpiece are completed; finally, the workpiece is transferred to a tempering furnace for final tempering (i.e., the conventional tempering in the background art), which can reduce the overall tempering time by N - 1 times, where N is the number of to-be-hardened surfaces. This saves the total tempering time, not only greatly improves the production efficiency, but also greatly reduces the energy consumption and production cost. In addition, compared with the induction hardening treatment, the present invention appropriately reduces the rotation speed of the workpiece during the induction tempering treatment, which is convenient for increasing the tempering time per unit length of the workpiece, and the working frequency during tempering is lower than that during hardening, which is convenient for utilizing the skin effect, that is, the low-frequency induction current can penetrate to a deeper depth, making the tempering depth deeper and reducing the risk of cracks in the race.

[0024] (2) The average depth of the hardened layer in the middle of the raceway of the main bearing ring product prepared by the present invention is 9.7 - 10.1 mm, the average surface hardness after quenching is 60.9 - 61.3 HRC, and the average surface hardness after tempering is 60.3 - 60.8 HRC, which is convenient for reducing the risk of cracks in the ring.

[0025] In addition to the purposes, features and advantages described above, the present invention has other purposes, features and advantages. The present invention will be further described in detail below with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0027] Figure 1 is a schematic structural diagram during the operation of an induction hardening and tempering method for a main bearing ring in Embodiment 1 of the present invention;

[0028] Figure 2 is a schematic structural diagram of a magnetic conductor;

[0029] Figure 3 is a schematic structural diagram of an induction coil;

[0030] Among them, 1 is a workpiece, 2 is a first inductor, 3 is a second inductor, A1 is a magnetic conductor, and A2 is an induction coil. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention. Embodiment 1:

[0032] See Figure 1 , an induction hardening and tempering method for a main bearing ring, including:

[0033] Step S1, install the workpiece 1 (specifically a main bearing ring provided by China Railway Construction Heavy Industry Group Co., Ltd.); hoist the workpiece 1 onto the workbench of the quenching machine tool, and after aligning the workpiece 1 (specifically adjusting the center of the workpiece 1 to coincide with the center of the workbench), clamp the workpiece 1;

[0034] Step S2, install the first inductor 2 and the second inductor 3; arrange the first inductor 2 and the second inductor 3 in sequence along the rotation direction of the workpiece 1;

[0035] Step S3: Set the quenching parameters and complete the induction quenching treatment of the currently to-be-quenched surface of the workpiece 1; on the quenching machine tool, set the rotation speed of the workbench driving the workpiece 1 to be 100 - 200 mm / min (specifically 110 mm / min); set the working power of both the first inductor 2 and the second inductor 3 to be 60 - 80 kW (specifically 74 kW); set the working frequency of both the first inductor 2 and the second inductor 3 to be 2.0 - 4.0 kHz (specifically 2.7 kHz); set the coupling gap between the first inductor 2 and the workpiece 1 and the coupling gap between the second inductor 3 and the workpiece 1 to be both 2 - 4 mm (specifically 2.5 mm); wherein, the coupling gap between the first inductor 2 and the workpiece 1 is the distance between the first inductor 2 and the workpiece 1; the coupling gap between the second inductor 3 and the workpiece 1 is the distance between the second inductor 3 and the workpiece 1; after setting the quenching parameters, start the quenching machine tool, the first inductor 2 and the second inductor 3 to complete the induction quenching treatment of the currently to-be-quenched surface of the workpiece 1;

[0036] Step S4: Set the tempering parameters and complete the induction tempering treatment of the currently to-be-quenched surface of the workpiece 1; on the quenching machine tool, set the rotation speed of the workbench driving the workpiece 1 to be 80 - 140 mm / min (specifically 90 mm / min); set the working power of both the first inductor 2 and the second inductor 3 to be 20 - 35 kW (specifically 26 kW); set the working frequency of both the first inductor 2 and the second inductor 3 to be 1.0 - 2.0 kHz (specifically 1.2 kHz); set the coupling gap between the first inductor 2 and the workpiece 1 and the coupling gap between the second inductor 3 and the workpiece 1 to be both 2 - 4 mm (specifically 2.5 mm); after setting the tempering parameters, start the quenching machine tool, the first inductor 2 and the second inductor 3 to complete the induction tempering treatment of the currently to-be-quenched surface of the workpiece 1;

[0037] Between the induction quenching treatment and the induction tempering treatment, a spray cooling treatment of the workpiece 1 is also included;

[0038] Step S5: Combine the induction quenching treatment and the induction tempering treatment to sequentially complete the quenching and tempering operations of the next to-be-quenched surface of the workpiece 1, and so on, until the quenching and tempering operations of all to-be-quenched surfaces of the workpiece 1 are completed.

[0039] The coolant used in the spray cooling treatment includes PAG quenching liquid; the mass concentration of the PAG quenching liquid used is 10% - 15% (specifically 14%), and the flow rate is 60 - 70 L / min (specifically 67 L / min).

[0040] The spraying method used in the spray cooling treatment is the jetting method.

[0041] The jetting method is completed by a spray box; along the rotation direction of the workpiece 1, the spray box is arranged behind the second inductor 3, and inclined spray holes are arranged on the spray box; the inclination direction of the spray holes deviates from the second inductor 3, and the included angle between its inclination direction and the workpiece surface is 10° to 60° (specifically 25°).

[0042] See Figures 1-3 , the first inductor 2 and the second inductor 3 have the same structure, and both include a magnetic conductor A1 (specifically, the American FLUXTROL A type solid magnetic conductor A1 is used and milled by a numerically controlled machine tool) and an induction coil A2; the magnetic conductor A1 is a rectangular structure with an opening; the induction coil A2 is a hollow copper rectangular square tube; the magnetic conductor A1 is integrally embedded in the induction coil A2 to facilitate concentrating magnetic induction lines and improving the heating efficiency of the induction coil A2. In addition, compared with the traditional silicon steel sheet, the magnetic conductor A1 milled can cover the induction coil A2 with the largest area and has a higher induction heating efficiency.

[0043] The induction hardening treatment and the induction tempering treatment further include a circulating cooling treatment for the first inductor 2 and the second inductor 3.

[0044] The circulating cooling treatment includes passing circulating cooling water into the induction coil A2 to cool the heat on the first inductor 2 and the second inductor 3 themselves during electromagnetic induction heating and the heat radiated from the workpiece 1 to the first inductor 2 and the second inductor 3. Embodiment 2:

[0045] Different from Embodiment 1, some quenching parameters and some tempering parameters are changed; specifically, in the quenching parameters, the working power of the first inductor 2 and the second inductor 3 is set to be 77 kW, and the coupling gaps between the first inductor 2 and the workpiece 1 and between the second inductor 3 and the workpiece 1 are both set to be 2.7 mm; in the tempering parameters, the working power of the first inductor 2 and the second inductor 3 is set to be 29 kW.

[0046] The main bearing ring products processed in Examples 1-2 were respectively subjected to tests on the depth of the hardened layer in the middle of the raceway, the surface hardness after quenching, the surface hardness after tempering, and magnetic particle flaw detection tests. The test results are shown in Table 1. Among them, the depth of the hardened layer in the middle of the raceway was tested using a sisco.kobelco hardened layer depth measuring instrument (model: Kobe Steel SH-67 of Japan). 100 test points were randomly selected, and the test results were the average values of each test point. The surface hardness after quenching was tested using a Leeb hardness tester (model: TIME5301). 100 test points were randomly selected, and the test results were the average values of each test point. The surface hardness after tempering was tested using a Leeb hardness tester (model: TIME5301). 100 test points were randomly selected, and the test results were the average values of each test point.

[0047] Table 1 Test Results of Hardened Layer Depth and Hardness

[0048]

[0049] As can be seen from the data in Table 1:

[0050] The average depths of the hardened layers in the middle of the raceways of the main bearing ring products prepared by the present invention using Examples 1-2 were 9.7 mm and 10.1 mm respectively, the average surface hardnesses after quenching were 61.3 HRC and 60.9 HRC respectively, and the average surface hardnesses after tempering were 60.8 HRC and 60.5 HRC respectively, which facilitated reducing the risk of cracks in the rings; and magnetic particle flaw detection tests also proved that there were no cracks on the surfaces of the main bearing ring products prepared by using Examples 1-2.

[0051] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for induction hardening and tempering of a main bearing race, characterized in that, Including: Step S1, installing the workpiece; hoisting the workpiece onto the workbench of the quenching machine tool, aligning the workpiece and then clamping the workpiece; Step S2, installing the first inductor and the second inductor; arranging the first inductor and the second inductor in sequence along the rotation direction of the workpiece; Step S3, setting the quenching parameters and completing the induction quenching treatment of the currently to-be-quenched surface of the workpiece; setting the speed of the workbench driving the workpiece to rotate on the quenching machine tool to be 100 - 200 mm / min; setting the working power of both the first inductor and the second inductor to be 60 - 80 kW; setting the working frequency of both the first inductor and the second inductor to be 2.0 - 4.0 kHz; setting the coupling gap between the first inductor and the workpiece and the coupling gap between the second inductor and the workpiece to be both 2 - 4 mm; after setting the quenching parameters, starting the quenching machine tool, the first inductor and the second inductor to complete the induction quenching treatment of the currently to-be-quenched surface of the workpiece; Step S4, setting the tempering parameters and completing the induction tempering treatment of the currently to-be-quenched surface of the workpiece; setting the speed of the workbench driving the workpiece to rotate on the quenching machine tool to be 80 - 140 mm / min; setting the working power of both the first inductor and the second inductor to be 20 - 35 kW; setting the working frequency of both the first inductor and the second inductor to be 1.0 - 2.0 kHz; setting the coupling gap between the first inductor and the workpiece and the coupling gap between the second inductor and the workpiece to be both 2 - 4 mm; after setting the tempering parameters, starting the quenching machine tool, the first inductor and the second inductor to complete the induction tempering treatment of the currently to-be-quenched surface of the workpiece; Between the induction quenching treatment and the induction tempering treatment, it also includes a spray cooling treatment of the workpiece; Step S5, combining the induction quenching treatment and the induction tempering treatment to sequentially complete the quenching and tempering operations of the next to-be-quenched surface of the workpiece, and so on until the quenching and tempering operations of all the to-be-quenched surfaces of the workpiece are completed; The structures of the first inductor and the second inductor are the same, and both include a magnetic conductor and an induction coil; the magnetic conductor is a rectangular structure with an opening; the induction coil is a hollow copper rectangular square tube; the whole magnetic conductor is embedded in the induction coil; The workpiece is a main bearing race; 2. The induction hardening and tempering method of the main bearing ring according to claim 1, characterized in that, The coolant used in the spray cooling treatment includes PAG quenching liquid; the mass concentration of the PAG quenching liquid used is 10% - 15%, and the flow rate is 60 - 70 L / min; 3. The induction hardening and tempering method for the main bearing ring according to claim 1, wherein, The spray method used in the spray cooling treatment is the jet method; 4. The induction hardening and tempering method for the main bearing race according to claim 3, characterized in that, The jet method is completed by using a spray box; along the rotation direction of the workpiece, the spray box is arranged behind the second inductor, and inclined spray holes are arranged on the spray box; the inclination direction of the spray holes deviates from the second inductor, and the included angle between its inclination direction and the workpiece surface is 10° - 60°.

5. The induction hardening and tempering method of the main bearing ring according to any one of claims 1 to 4, characterized in that, The induction hardening treatment and the induction tempering treatment further include a circulating cooling treatment for the first inductor and the second inductor.

6. The induction hardening and tempering method for the main bearing ring according to claim 5, characterized in that The circulating cooling treatment includes passing circulating cooling water into the induction coil.

7. A product prepared by using the method for induction hardening and tempering of a main bearing ring according to claim 6.

8. The product according to claim 7, characterized in that, The average depth of the hardened layer in the middle of the raceway of the product is 9.7 - 10.1 mm, the average surface hardness after quenching is 60.9 - 61.3 HRC, and the average surface hardness after tempering is 60.3 - 60.8 HRC.

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