Induction hardening treatment method and application of large bearing ring

Abstract

An induction hardening treatment method for a large bearing ring comprises the following steps: 1) austenitizing: heating the bearing ring by using inductors (ir1, ir2 and Ib) to enable the surface temperature of the bearing ring to reach an austenitizing temperature; and (2) martensite treatment: spraying cooling liquid to the bearing ring by using sprayers (sr, sb), so that the bearing ring is quickly cooled, and austenite in the structure of the bearing ring is converted into martensite. The austenitizing step is carried out by simultaneously heating the raceway-side surface (fr) and the raceway-back-side surface (fb) of the bearing ring by means of an inductor (i). On the basis of the method, the invention further provides an induction heating quenching machine tool for the large bearing ring. The double-side heating not only enables the bearing ring to be subjected to double-side hardening, but also can adjust the forming depth of the hardened layer below the two side surfaces of the bearing ring. The deepest depth can reach the core part of the bearing ring, so that the hardened layer is formed in the whole thickness range of the bearing ring, and the material performance required by different applications is met to the maximum extent.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for induction hardening of a large bearing ring, and an induction heating and quenching machine bed for hardening a large bearing ring by using the method. BACKGROUND

[0002] Induction quenching is increasingly used in the surface hardening process of large bearing rings with a diameter of 500 mm or more. The "induction quenching" refers to a heat treatment process in which an electric induction heater (hereinafter referred to as "inductor") is used to heat the surface of at least the raceway portion of the bearing ring to an austenitizing temperature (for the purpose of obtaining uniform austenite grains), and then a uniform and fine martensite and granular cementite complex structure is formed by rapid cooling. This process can improve the hardness, strength and wear resistance of the raceway surface of the bearing ring.

[0003] Figure 1 Taking a double-row inner ring of a self-aligning roller bearing as an example, a schematic diagram of a conventional induction hardening process for heating the surface of the side of the bearing ring with raceways (hereinafter referred to as "raceway side") is shown. This method only heats the raceway side surface f r , resulting in inconsistent temperatures between the core f c and the raceway side surface f r of the bearing ring: the raceway side surface f r near the inductor i is high in temperature, the raceway back surface f b far from the inductor i is low in temperature, and the temperature of the core f c is between the above two. The lower temperatures in the raceway back f b and the core f c prevent the ferrite in the two from being transformed into austenite, so that the ferrite in the two cannot be transformed into martensite after cooling. The above reasons cause the raceway back and the core to be inferior to the raceway side in strength, hardness and wear resistance. If the temperature of the raceway side is increased to allow the temperature of the core and the raceway back to reach the austenitizing temperature, the excessively high temperature of the raceway side will cause the austenite grains therein to become coarse, so that the residual austenite after cooling increases and cannot be fully transformed into martensite. Therefore, excessive heating of the raceway side is not conducive to the improvement of the strength and toughness of the surface thereof.

[0004] The reality calls for an induction hardening process and equipment that can improve the strength and toughness of the bearing ring in a larger thickness range. SUMMARY

[0005] To solve the above technical problems, the present application provides a surface hardening treatment method for a large bearing ring, which comprises the following sequential steps: 1) an austenitizing step: heating the bearing ring with an inductor (i) to make the surface temperature of the bearing ring reach the austenitizing temperature; and 2) a martensitizing step: spraying a cooling liquid on the bearing ring with a sprayer to rapidly cool the bearing ring, so that the austenite in the organization of the bearing ring is converted into martensite. The austenitizing step is achieved by simultaneously heating the raceway side surface and the raceway backside surface of the bearing ring with the inductor.

[0006] The double-sided heating makes the raceway backside of the bearing ring also be able to obtain induction hardening treatment, so that the bearing ring is double-sided hardened. More importantly, after the double-sided surfaces are heated to the austenitizing temperature, by maintaining the austenitizing temperature for a predetermined time, the heat conduction mechanism can conduct heat to a predetermined depth below the two-sided surfaces of the bearing ring, and the deepest can reach the core of the bearing ring. The continuously maintained austenitizing temperature not only makes the austenite composition more uniform, but also enables the austenitizing to be achieved at a predetermined depth below the surface of the bearing ring, until the entire (thickness) range of the bearing ring including the core is austenitized. In short, the double-sided heating not only enables the bearing ring to be double-sided hardened, but also enables the formation depth of the hardened layer below the two-sided surfaces of the bearing ring to be adjusted. The depth can be the deepest to reach the core of the bearing ring, so that the hardened layer is formed in the entire thickness range of the bearing ring, and the material properties required by different applications are maximally met.

[0007] On the basis of the above method, the present application further provides an induction heating and quenching machine tool for a large bearing ring, which comprises a driving mechanism, an inductor and a sprayer. The driving mechanism is used to drive the bearing ring to be positioned and rotated, the inductor is used to induction heat the bearing ring to make the surface temperature thereof reach the austenitizing temperature when the bearing ring is rotating, and the sprayer is used to spray a cooling liquid on the austenitized bearing ring to make the austenite in the organization of the bearing ring be converted into martensite. The inductor is arranged to simultaneously heat the raceway side surface and the raceway backside surface of the bearing ring.

[0008] The machine tool is arranged to be able to heat the double-sided surfaces of the bearing ring, and thus has the beneficial effects of the above double-sided heating method. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 A schematic diagram showing the method of induction heating only the raceway side surface of the bearing ring in the prior art;

[0010] Figure 2 A schematic diagram showing the method of simultaneously induction heating the raceway side and the raceway backside of the bearing ring according to the present application;

[0011] Figure 3A andFigure 3B A schematic view of the induction hardening method of the first embodiment of the present application is shown from a different perspective;

[0012] Figure 3C A schematic view of the induction hardening method of the first embodiment of the present application is shown from a different perspective; Figure 3A A schematic view of the induction hardening method of the first embodiment of the present application is shown from a different perspective; Figure 3B A schematic view of the induction hardening method of the first embodiment of the present application is shown from a different perspective;

[0013] Figure 4 A schematic view of the induction hardening method of the second embodiment of the present application is shown from a different perspective; and

[0014] Figures 5A-5C A schematic view of the induction hardening method of the third embodiment of the present application is shown from a different perspective. DETAILED DESCRIPTION

[0015] In the following description, like reference numerals are used to refer to like parts throughout particular embodiments and the drawings. The terms directional terms, such as "axial", "radial" and "circumferential", unless otherwise defined or indicated, refer to the axial, radial and circumferential directions of the component being described.

[0016] Figure 2 A schematic view of the induction hardening method of the first embodiment of the present application is shown from a different perspective; and r A schematic view of the induction hardening method of the first embodiment of the present application is shown from a different perspective; b A schematic view of the induction hardening method of the first embodiment of the present application is shown from a different perspective; r A schematic view of the induction hardening method of the first embodiment of the present application is shown from a different perspective; b A schematic view of the induction hardening method of the first embodiment of the present application is shown from a different perspective; Figure 3A , Figure 3B and Figure 3C A schematic view of the induction hardening method of the first embodiment of the present application is shown from a different perspective; r A schematic view of the induction hardening method of the first embodiment of the present application is shown from a different perspective; b A schematic view of the induction hardening method of the first embodiment of the present application is shown from a different perspective; Figure 1 A schematic view of the induction hardening method of the first embodiment of the present application is shown from a different perspective; Figures 2-4 A schematic view of the induction hardening method of the first embodiment of the present application is shown from a different perspective;

[0017] Figure 3A A schematic view of the induction hardening method of the first embodiment of the present application is shown from a different perspective; and Figure 3B A schematic view of the induction hardening method of the first embodiment of the present application is shown from a different perspective; andi1 G i2 The inductors are fixedly distributed along the circumference of the bearing ring. Theoretically, the higher the distribution density of the inductor array and the more uniform the circumferential spacing, the better it is for improving the hardening uniformity of the bearing ring.

[0018] In the first embodiment described above, at least two sets of sensor groups G i1 G i2 Each includes two short-type sensors i on the raceway sides covering the double-row raceways r1 and r2. r1 i r2 and a long sensor I covering the back side of one raceway of the double-row raceways r1 and r2 b The short-type sensor i on the raceway side r1 i r2 This refers to the surface f that fits (parallel to) the raceway side of the bearing ring. r However, its length only covers the sensor of one of the two raceways r1 and r2. The elongated sensor I on the back side of the raceway... b This refers to the shape-fitting (parallel) raceway back surface f of the bearing ring. b The length is sufficient to cover the entire back side of the sensors along the double-row raceways r1 and r2. In other words, in each sensor group G of the first embodiment... i1 G i2 In the middle, the raceway-side sensor includes two short sensors i that respectively cover the double-row raceways r1 and r2. r1 i r2 The raceway backside sensor consists of only one elongated sensor I covering the entire backside surface of the double-row raceways r1 and r2. b .

[0019] In a preferred embodiment, the inductor is configured to maintain the austenitizing temperature at both sides of the bearing race for a predetermined period of time after the austenitizing temperature is reached, so that the thermal conductivity effect can conduct heat to a predetermined depth below the bearing race surface. This method allows adjustment of the hardening depth (i.e., the thickness of the hardened layer) on both sides of the bearing race according to application requirements, thereby obtaining the material properties required for different load types. As a further preferred embodiment, the long and short inductors can each have independent coils and power supplies to provide the power input required to maintain the austenitizing temperature.

[0020] After the austenitization step is completed, such as Figure 3C As shown, all sensors i r1 i r2 and I b It is configured to recede from a position close to the bearing race to a predetermined safe distance, so as to allow the sprayer to stop heating the bearing race while simultaneously allowing the sprayer to... r s bRapid cooling (i.e., martensitization) is performed on the bearing race. In this invention, rapid cooling is achieved by spraying coolant onto the bearing race using a sprayer. The coolant can be water or an aqueous solution of certain polymers (e.g., polyalkylene glycol-based polymers). The temperature of the aqueous solution and the polymer concentration can be set to prevent cracking of the bearing race during the hardening process.

[0021] Similar to the situation with sensors, sprayers r s b It is also set for the raceway side surface f of the bearing ring. r and the back surface of the raceway f b Simultaneous spray cooling is implemented. The sprayers are arranged in sprayer group G. s1 G s2 The sprayers are fixedly distributed in a circumferential pattern on the bearing ring. The number of sprayer groups is at least two, preferably symmetrically distributed circumferentially on the bearing ring. Theoretically, the higher the distribution density of the sprayer groups and the more uniform the circumferential spacing, the better it is for improving the hardening uniformity of the bearing ring.

[0022] exist Figure 3A In the embodiment shown, the sprayer group G s1 G s2 Includes raceway side surface f for bearing rings r The raceway side sprayers are used for cooling. r and for the raceway back surface f of the bearing ring b The raceway backside sprayers are used for cooling. b As an alternative, sprayer assembly G s1 G s2 It can also be configured as a single sprayer (not shown). This single sprayer is configured to simultaneously spray the raceway side surface f of the bearing ring. r and the back surface of the raceway f b Implement spray cooling. It is easy to understand that as long as both sides of the bearing ring can be cooled simultaneously, the sprayer and sprayer group are not limited by specific structure and configuration quantity.

[0023] Figure 4 This diagram illustrates a second embodiment of the present invention, whereby an inductor array heats both sides of the bearing ring. Unlike the first embodiment, each inductor array G... i1 G i2 Each includes a raceway-side elongated sensor I covering the double-row raceways r1 and r2. r and a long sensor I covering the back side of the double-row raceway. bIn the second embodiment, the bearing ring is heated by long inductors on both the raceway side and the raceway back side. The advantage of the long inductors is that the raceway side surface f r and the raceway back side surface f b are both uniformly heated, so the thermal deformation range is small, but the disadvantage is that the shape of the raceway side long inductor I r is complex and difficult to manufacture.

[0024] Figure 5A and Figure 5B Further shows a method schematic diagram of the third embodiment of the present application. Unlike the first and second embodiments, in the third embodiment, the bearing ring is heated by raceway side short inductors i r , i b covering only a single row of raceways on the raceway side surface f r1 , f r2 and short inductors i b1 , i b2 covering only a single row of raceway back sides. The advantage of the short inductors is that they are easy to manufacture, but the disadvantage is that if the circumferential positions of the double rows of raceways r1, r2 are not consistent, the thermal deformation range of the bearing ring will increase.

[0025] In the embodiments shown in Figure 5A and Figure 5B , the first inductor group G i1 includes a first raceway side short inductor i r1 covering the first raceway r1 and a first raceway back side short inductor i b1 covering the back side of the first raceway r1, and the second inductor group G i2 includes a second raceway side short inductor i r2 covering the second raceway r2 and a second raceway back side short inductor i b2 covering the back side of the second raceway r2. Since the circumferential positions of the two inductor groups G i1 and G i2 on the double rows of raceways r1 and r2 are not consistent, the heating of the bearing ring on the double rows of raceways r1 and r2 is also not consistent. This will cause an increase in the thermal deformation range of the double bearing ring.

[0026] To overcome the above-mentioned defects, an improved method is to make the inductor groups G i1 , G i2 have as consistent circumferential distribution as possible on the double rows of raceways r1, r2 of the bearing ring. Still taking the embodiments shown in Figure 5A and Figure 5B as examples, the inductor group G i1 of the first raceway r1 can be made to have the same circumferential distribution as the inductor group G i2 of the second raceway r2.are located at one place (not shown) in the circumferential direction of the bearing ring. Alternatively, as shown in Figure 5C Fig. 6, one inductor group G i3 and G i4 may be added to each of the double-row raceways r1 and r2, so that the inductor groups G i1 , G i3 on the raceway r1 and the inductor groups G i2 , G i4 on the raceway r2 are uniformly distributed in the circumferential direction.

[0027] On the basis of the above method, the present application further provides an inductive heating and quenching machine for large bearing rings, comprising a driving mechanism, an inductor and a sprayer. The driving mechanism is used to drive the bearing ring to rotate and position, the inductor is used to inductively heat the bearing ring when it rotates, so that the surface temperature of the bearing ring reaches the austenitizing temperature, and the sprayer is used to spray cooling liquid on the austenitized bearing ring, so that the austenite in the structure of the bearing ring is converted into martensite. The inductor is arranged to heat the raceway side surface and the raceway backside surface of the bearing ring at the same time. The machine is arranged to be able to heat and cool the bearing ring in the state of rotation, which can greatly improve the production efficiency compared with the case where the bearing ring is processed in the state of static.

[0028] The bearing ring induction hardening method described above and its application in the equipment level are not limited by the specific embodiments, and the more general technical solutions will be subject to the limitations in the appended claims. Any changes and improvements to the present application, as long as it meets the limitations of the appended claims, belongs to the protection scope of the present application.

Claims

1. A method for induction hardening treatment of large bearing rings, comprising the following sequential steps: 1) Austenitization step: using a sensor (i r1 i r2 I b The bearing ring is heated until its surface temperature reaches the austenitizing temperature; and 2) Martensitization step: using a sprayer (s) r s b Spray coolant onto the bearing ring to cool it rapidly, thereby transforming the austenite in its microstructure into martensite. Its features are: The austenitizing step is performed using a sensor (i r1 i r2 I b ) for the raceway side surface of the bearing ring (f r ) and raceway back surface (f b This is achieved through simultaneous heating.

2. The method according to claim 1, characterized in that: In the austenitizing step, after the bearing ring reaches the austenitizing temperature, it is held at that temperature for a predetermined period of time so that a predetermined depth below the surface of the bearing ring is also austenitized through heat conduction.

3. The method according to claim 1 or 2, characterized in that: The martensitization step is performed using a sprayer (s) r s b ) for the raceway side surface of the bearing ring (f r ) and raceway back surface (f b This is achieved by spraying coolant at the same time.

4. An induction heating quenching machine tool for large bearing rings, comprising: A drive mechanism is used to drive the bearing ring to perform a positioning rotation; Sensor (i r1 i r2 I b ), used to induction heat the bearing rings as they rotate, so that their surface temperature reaches the austenitizing temperature; and Sprayer (s) r s b This is used to spray coolant onto austenitized bearing rings, causing the austenite in the bearing ring structure to transform into martensite. Its features are: The sensor (i r1 i r2 I b ) is set to the raceway side surface of the bearing ring (f r ) and raceway back surface (f b Heating is performed simultaneously.

5. The induction heating quenching machine tool according to claim 4, characterized in that: The sensor (i r1 i r2 I b ) with sensor group (G i1 G i2 The sensors are fixedly distributed in the form of at least one location in the circumferential direction of the bearing ring, and each of the sensor groups includes a sensor for sensing the raceway side surface (f) of the bearing ring. r The raceway-side sensor (i) is used for heating. r1 i r2 ) and for the raceway back surface of the bearing ring (f b The raceway back-side sensor (I) is used for heating. b ).

6. The induction heating quenching machine tool according to claim 5, characterized in that: The sprayer (s) r s b ) with sprayer group (G s1 G s2 The sprayers are fixedly distributed in the form of at least one position in the circumferential direction of the bearing ring, and each of the sprayer groups (G) s1 G s2 All of these include raceway side surfaces (f) for the bearing rings. r The raceway side sprayers are used for cooling. r ) and for the raceway back surface of the bearing ring (f b The raceway backside sprayer (s) is used for cooling. b ).

7. The induction heating quenching machine tool according to any one of claims 4 to 6, characterized in that: The bearing ring is either the inner ring of a double-row bearing or the outer ring of a double-row bearing.

8. The induction heating quenching machine tool according to claim 7, characterized in that: Each of the sensor groups (G) i1 G i2 Each of these includes a raceway-side elongated sensor (I) covering the double-row raceways (r1, r2) of the bearing rings. r ) and a long sensor (I) on the back side of one raceway covering the double-row raceway (r1, r2) of the bearing ring. b ).

9. The induction heating quenching machine tool according to claim 7, characterized in that: Each of the sensor groups (G) i1 G i2 Each of these includes a short-type sensor (i) on the raceway side covering one of the double-row raceways (r1, r2) of the bearing ring. r1 i r2 ) and a short sensor on the back side of the raceway covering one of the double-row raceways (i b1 i b2 ).

10. The induction heating quenching machine tool according to claim 7, characterized in that: Each of the sensor groups (G) i1 G i2 Each of these includes two short-type sensors (i) on the raceway side covering the double-row raceways (r1, r2) of the bearing ring. r1 i r2 ) and a long sensor (I) on the back side of one raceway covering the double-row raceway (r1, r2) of the bearing ring. b ).

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